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Behavioral and Environmental Countermeasures of Sleep Loss
Short-Term Countermeasures for Sleep Loss Effects
Contents Behavioral and Environmental Countermeasures of Sleep Loss Naps
Behavioral and Environmental Countermeasures of Sleep Loss C Poon and K A Hardin, University of California, Sacramento, CA, USA ã 2013 Elsevier Inc. All rights reserved.
Glossary Cognitive–behavioral therapy: A form of treatment that utilizes different behaviors and environmental factors to alter unhealthy thinking patterns and associated behaviors. Phase advance: A condition in which sleep begins and ends earlier than the desired time for sleep. Phase delay: A condition in which sleep begins and ends later than the desired time for sleep. Sleep architecture: The structure and pattern of sleep which can be divided into different sleep stages differentiated by brain activity on an electroencephalogram. Sleep debt: A condition where the quantity of sleep is insufficient to support the normal alertness, performance, or health of an individual.
Introduction Sleep deprivation is an extremely common problem in the United States affecting 10–20% of the population. Studies by the National Sleep Foundation show that approximately 20% of Americans report sleeping 6.5 h or less per night. Populations at high risk for sleep loss include shift workers such as airplane pilots, the elderly, and individuals with psychological, medical, or pain syndromes. Both acute and chronic sleep loss can lead to physical, mental, and even psychological impairment. The full impact of fatigue is often underappreciated, but many of its effects have long been known. The most significant symptom associated with sleep deprivation is hypersomnolence. Hypersomnolence can have a significant impact on behavioral characteristics, such as cognitive performance, reaction time, attention, and alertness. Compared to people who are well-rested, individuals who are sleep-deprived think and move more slowly, make more mistakes, and have memory difficulties. A significant increase in accidents occurs in people who report less than 7 h of sleep per night. After a single night of inadequate sleep (< 5 h), driving performance significantly decreases, and
Encyclopedia of Sleep
http://dx.doi.org/10.1016/B978-0-12-378610-4.00075-9
Sleep deprivation: The condition of not having adequate sleep quantity or quality. Sleep homeostasis: The constant, finely regulated balance of sleep duration and intensity. Sleep hygiene: Sleep habits; good sleep hygiene practices include setting standardized bedtime and awakening times, avoiding reading or watching television in bed, avoiding naps, and remaining in bed only when sleepy. Sleep latency: The time from lights out to sleep onset. White noise: A type of noise produced by combining sounds of all frequencies together. Because it contains all frequencies, it often masks specific sounds making them indistinguishable.
unfortunately, most drivers underestimate their impairment. As a result, excessive sleepiness is one of the leading causes of automobile crashes and major professional trucking crashes in the United States. Individuals with chronic sleep loss also have higher incidences of stomach problems, such as heartburn and indigestion, infections, weight gain, and cardiovascular problems. Mortality has been shown to increase in individuals who chronically sleep less than 5 h per night. Given the profound consequences associated with sleep deprivation, countermeasures are needed to prevent sleep loss and combat its associated symptoms. This article will review the behavioral and environmental factors to prevent and counteract the effects of sleep loss. Details of chronic sleep deprivation, prevention, and treatment are discussed in other articles (Table 1).
Countermeasures to Prevent Sleep Loss Recurrent sleep loss of even small amounts will eventually perpetuate a state of chronic sleep deprivation. Therefore,
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Short-Term Countermeasures for Sleep Loss Effects | Behavioral and Environmental Countermeasures of Sleep Loss
Table 1
Summary of behavior countermeasures for sleep loss
Strategy
Description
Sleep hygiene
Habits and behaviors that promote effective sleep onset and maintenance Method used to prevent the association between the bedroom and increased wakefulness Technique that sets a specific schedule of being in bed in order to improve the homeostatic drive to fall asleep A technique that uses a combination of behaviors and environmental factors to remove unhealthy thoughts and beliefs about one’s ability to fall asleep Methods including muscle relaxation, biofeedback, and guided imagery to reduce stress in preparation for sleep Using activities such as a 5-min walk or standing in order to temporarily increase alertness The use of short 5–20-min breaks to improve cognitive function in continuous tasks Cool temperature can be used to improve alertness in limited studies Bright light regulates the circadian rhythm and can be used to improve alertness, especially in shift workers at night Loud noise can decrease somnolence in sleep-deprived individuals Short naps can temporarily improve alertness that results from prolonged sleep deprivation
Stimulus control Sleep restriction
Cognitive– behavioral therapy Relaxation therapy
Activity Rest breaks Temperature Light
Noise Naps
Table 2
• • • • • • • • • •
Sleep hygiene rules
Sleep only as much as needed and then get out of bed Keep a regular sleep schedule Exercise regularly but at least 4–5 h before bedtime Avoid caffeine after lunch Avoid alcohol near bedtime Avoid smoking Do not go to bed hungry Adjust bedroom environment to decrease stimuli Resolve your worries before bedtime Avoid forcing sleep
returning to a normal sleep schedule as soon as possible remains an important part of recovery. Behavior and environmental factors can be useful in helping individuals return to a regular, rejuvenating sleep schedule.
Sleep Hygiene There are many factors that can cause sleep loss, such as change in environment associated with traveling, bedtime habits, shift work, and military action. After a prolonged period, patients eventually need to recover from their sleep debt. Practicing good sleep hygiene remains an important part of recovery. It also helps to prepare individuals expecting to enter a period of sleep deprivation. The term refers to behaviors which improve quantity and quality of sleep. Originally, it was used by Peter Hauri and colleagues to improve symptoms of insomnia in 1977. These rules were primarily derived by observing
common practices of patients with poor sleep. Although these recommendations have evolved since their original description, they still aim to avoid behaviors that interfere with normal sleep and encourage behaviors that promote good sleep (Table 2).
Stimulus Control When people are exposed to a different or changing environment, they often have difficulty falling or staying asleep. Temporary and long-term techniques can be used to prevent the psychological association between bedtime and staying awake. Stimulus control therapy tries to separate the association between going to bed and increased arousal. Spending time awake in bed strengthens the association between wakefulness and the bedroom. The longer one stays in bed trying to sleep, the stronger the association becomes. This perpetuates difficulty falling asleep. The goal of stimulus control is to increase the likelihood of sleep by disrupting the association between the bedroom and wakefulness. Patients should go to bed only when drowsy and ready to sleep. The bedroom should not be used for other activities such as reading, watching television, or eating. If a patient has difficulty falling asleep while in bed for a prolonged period, he or she should get out of bed, engage in a relaxing activity, and return only when sleepy. The process is repeated if the patient still cannot sleep for more than 20 min. An alarm clock should be set to wake the patient at the same time every morning to encourage a steady sleep schedule. Many studies have found stimulus control to be effective in promoting effective sleep. It has been most successful in improving sleep onset and sleep maintenance.
Sleep Restriction Many patients have difficulty falling asleep and stay in bed for prolonged periods. Their wake and bedtimes often occur at irregular times. This results in shifts of the normal circadian system and increased somnolence at inappropriate times. Sleep restriction therapy, similar to stimulus control, attempts to limit the amount of time patients spend in bed but provides a daily schedule to follow for going to bed and waking. The process begins by keeping a sleep diary to document the patient’s usual amount of sleep. The patient then decreases the amount of time in bed to the amount of sleep reported in these diaries. A consistent wake time is also scheduled. As patients spend less time in bed, there is an increase in the normal homeostatic drive to sleep. Bedtime is then advanced earlier until the desired schedule is achieved. Any worsening of sleep efficiency results in a later bedtime. Eventually, patients become accustomed to going to bed and falling asleep quickly. One disadvantage of this technique is increased daytime somnolence during the initial phase of treatment. Many patients also resist the idea of going to bed later since it reduces their available time to obtain sleep. It is best to start the sleep restriction process when the patient has several days to acclimatize, such as the weekend away from the work environment. This will decrease the stress related to the initial decrease in daytime functioning due to hypersomnolence.
Short-Term Countermeasures for Sleep Loss Effects | Behavioral and Environmental Countermeasures of Sleep Loss
A study with 21 elderly patients compared sleep hygiene alone with combined sleep restriction and sleep hygiene. Patients in the sleep restriction group obtained a significantly greater increase in sleep efficiency, self-reported mood on awakening, and sleep continuity. The results indicated that sleep restriction therapy had a very sustainable effect 1 year later.
Cognitive Behavioral Therapy Combating sleep loss symptoms requires understanding factors that may influence delayed sleep onset. Some classic hallmarks of difficulty falling asleep include irrational fears, unrealistic expectations, and excessive worrying about sleep. Patients with these difficulties may be preoccupied with the thought of falling asleep. They worry about daytime impairments in their occupation and health because of sleep deprivation. These fears place pressure on an individual to fall asleep. Cognitive therapy challenges these beliefs and fears in order to restructure an individual’s negative outlook. As a result, the anxiety associated with sleep at bedtime decreases. Cognitive behavioral therapy combines cognitive therapy with the previously mentioned nonpharmacologic therapies such as sleep restriction, sleep hygiene, and stimulus control. Additionally, reasons and consequences of the patients’ thoughts and concerns regarding impairment to their sleep are addressed in weekly sessions. The goal of this combined therapy is to simultaneously change the abnormal sleep habits and cognitive outlook of sleep. A sample program may begin with a session focusing on stimulus control and sleep restriction. The next session may teach proper sleep hygiene and cognitive therapy. The course ends with a session that integrates the other lessons and addresses potential problems in maintenance of a proper sleep schedule. These sessions have shown lasting improvements on sleep onset and maintenance. This occurs by forming habits in individuals that encourage sleep. In addition, this approach offers treatment for patients such as older adults, pregnant women, or patients with specific medical illnesses who cannot take sedative medications. Unfortunately, few clinicians have been formally trained to provide cognitive behavioral therapy, and its benefits may be reduced when administered by less experienced individuals. Despite prolonged use, cognitive behavioral therapy does not seem to have significant adverse long-term effects.
Relaxation Therapy Individuals who have significant psychological or physical stress will also have difficulties recovering from sleep deprivation. Relaxation therapy attempts to improve hyperarousal in order to allow adequate sleep. There are several techniques described to achieve this goal including progressive muscle relaxation, biofeedback, and guided imagery. Progressive muscle relaxation was initially developed by Edmund Jacobsen in the 1930s. It was specifically applied to treat difficulties sleeping. The patient is instructed to tense and then systematically relax various areas of the body. Eventually the whole body is relaxed. Several studies suggest a positive impact on sleep. At least one trial involving 57 patients with sleep deprivation treated with progressive relaxation therapy showed improved sleep onset. Other limited studies show improvements in different sleep parameters.
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Biofeedback teaches relaxation by providing patients with a signal that measures their level of stress. Usually this technique employs electroencephalogram (EEG) or electromyogram (EMG) to signal an increase in tension. In a typical session, the patient will learn how to better relax by focusing on their feedback signal when it shows an increase in stress. This technique, however, is not commonly used, partly due to its duration and intensity. Often, patients may also require between 30 and 90 sessions to successfully master this form of relaxation. Guided imagery involves having a patient imagine and meditate on a relaxing scene. Scenes commonly used include lying on a beach, taking a hot bath, or sitting in front of a warm fire. When a patient becomes efficient at this task, they can induce relaxation quickly by focusing on the visual image. This relaxation therapy technique is helpful in patients with increased cognitive arousal since it offers a distraction from their usual worries. Each of these therapies improves the hyperarousal state that prevents individuals from going to sleep. While many articles and studies suggest that these treatments provide a benefit, additional studies on their efficacy are still needed.
Countermeasures to Combat the Effects of Sleep Loss If adequate sleep cannot be obtained, various measures can be used to prevent or minimize the effect of sleep loss. Upon discovering signs of diminishing performance and somnolence, individuals can use activity, environmental factors, or even stimulants to temporarily improve their alertness. Unfortunately, sleep is a biological need and sheer determination or willpower cannot offset the mounting effects of inadequate sleep.
Activity In early sleep deprivation, brief periods of activity can temporarily improve somnolence. Sleep latency tests have been widely used to illustrate this concept. For example, in one study, 18 healthy subjects underwent five sleep latency tests after two nights of sleep deprivation. One of these tests was performed after a 5-min walk. The test was repeated on 2 separate weeks. The results showed a significant increase in sleep latency after the 5-min walk. Heart rate also increased shortly after activity, suggesting increased arousal. The study illustrates that short periods of activity such as a 5-min walk can temporarily reverse the effects of hypersomnolence. Another study evaluated 14 normal young adults with maintenance of wakefulness tests after being awake for 7, 19, and 31 h. During these tests, subjects were required to do various activities such as standing, performing knee bends, or quietly listening to someone talking. Wakefulness improved significantly while subjects were standing and performing knee bends compared to listening to someone talking. This improvement diminished over longer wake periods. As a result, the benefits of activity may only be effective with early or milder sleep loss. In addition, prolonged activity may actually worsen fatigue over time.
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Rest Periods Short breaks can increase alertness by reducing the conscious disengagement of monotonous tasks. Although not as effective as other countermeasures, brief periods of rest from a continuous task can serve to acutely improve alertness and performance. A recently published study evaluated the effects of total break time on individuals performing data entry. Four 5-min supplemental breaks were added to the two standard 15-min breaks in a workday. After 4 weeks, the workers who received an additional 20 min of break time per day had significantly faster data entry speeds without loss of productivity. There were also reductions in reports of physical discomfort. Breaks can also have a positive impact on individuals experiencing partial or total sleep loss. At least two separate protocols have studied subjects who had 54 and 64 h of continuous wake time. Individuals who received five 20-min rest breaks during required tasks showed improvements in performance, alertness, fatigue, and mood compared to those who received no breaks. These data have been useful in the schedules of military pilots where breaks have been used to overcome somnolence and fatigue in sustained operations. However, these improvements in performance may not occur in all situations. One study evaluating industrial engineers found that mishaps occurred more frequently with 15-min breaks every 2 h. The study suggests that improvements in performance with rest breaks should take into account the nature of the task itself.
Temperature Another factor that affects sleep onset is temperature. Typically, temperature follows a diurnal pattern that decreases during periods of energy conservation. Core body temperature decreases in the late evening usually reaching a nadir at approximately 2 a.m. and is associated with an increase in homeostatic need for sleep. This decrease in core body temperature is not limited by circadian rhythm, however, since temperature also decreases during naps. Many studies have evaluated whether adjustments in core or distal body temperature can affect sleep onset. ‘Passive body heating’ through the use of hot baths has shown improvements in the depth and quality of subsequent sleep. These studies were performed in both normal sleepers and older adults. Distal body temperature warming relative to core body temperature seems to have the most profound effect on sleep onset. Patients with sleep onset insomnia also have improved sleep onset with mild warming of their distal extremities. Because adjustments in body temperature seem to affect the onset of sleep, several studies have looked at temperature as a way to improve wakefulness. Unfortunately, a consistent benefit has not been shown during sleep loss. One study required 16 young adult drivers to drive an interactive car simulator for 2.5 h with the air conditioner blowing cold air in their face during the afternoon after they had received only 5 h of sleep the previous night. They were evaluated for ‘incidents’ of drifting over lane markings when compared to a group who did not drive with the air conditioner. The study did not show a significant difference between total numbers of mistakes.
However, there was a trend toward fewer ‘incidents’ with both radio and cool air during the first 30 min of driving. Another study did show that heat up to 92 F was effective in improving performance during vigilance tasks after sleep deprivation. Results suggest that changes in ambient temperature may have some effect on the symptoms of sleep deprivation. However, further studies would be required to further evaluate these findings.
Light Bright light can be a source of stimulation. Studies show that the circadian rhythm adjusts to the surrounding light–dark schedule. Light exposure during the habitual night shifts sleep onset later (phase delay) while exposure in the early morning can cause it to shift earlier (phase advance). From these observations, light may act as a source of stimulation to prevent the effects of acute sleep loss. One study evaluated the effect of bright light compared to dim light on patients required to do repetitive mental tasks. Those patients who were exposed to bright light had delayed heart rate decline that normally accompanies sleep onset. There was also less heart rate variability during repetitive mental tasks. The study suggests that bright light exposure delays the nocturnal decrease in heart rate and maintains autonomic balance needed for mental tasks. It also illustrates how bright light can delay the physiologic changes that accompany sleep onset. A recent review of the literature also concluded that light may exert an alerting effect in the evenings. These alerting effects may be tied to suppression of melatonin, which is normally released in the mid to late night. Light therefore has the potential to slow decline in performance and alertness that often occurs prior to falling asleep. Some evidence also suggests that these alerting effects are independent of the time of day. If true, it suggests that light may be an effective therapy to improve alertness and performance impairment from sleep loss.
Noise Individuals who try to sleep usually benefit from a quiet environment away from intermittent noises and disruptions. Sudden loud noises become more disruptive to sleep than continuous noises. In fact, monotonic noises such as the sound of a fan, also known as white noise, can be helpful in masking environmental stimuli. Earplugs can also be used to block excess noise and promote sleep onset. Counterintuitively, loud noise may have a beneficial effect on hypersomnolence during sleep deprivation. Although performance often worsens in well-rested individuals, loud, stimulating noise may temporarily improve the effects from sleep deprivation. Noise levels below 40 decibels are required for a normal individual to fall asleep. As a reference, a busy office has an average noise level of 70 dB. The front-row seats of a rock concert may have a noise level of 110 dB. Any increase in noise intensity can cause arousals from sleep. Some studies show that exposure to noise levels found in a hospital intensive care unit results in a decrease in total sleep time, total rapid eye movement (REM) sleep, sleep efficiency, REM sleep latency,
Short-Term Countermeasures for Sleep Loss Effects | Behavioral and Environmental Countermeasures of Sleep Loss
and number of arousals. However, large studies still need to be performed to fully characterize the effects of noise on sleep loss.
Naps A full review of naps will be discussed in a separate chapter. Briefly, naps are a very effective nonpharmacological technique for restoring alertness. Several studies have documented how naps taken during long periods of continuous wakefulness can be extremely beneficial. For example, airplane pilots who take an average of a 26-min nap during a prolonged flight showed significant improvement in subsequent alertness and psychomotor performance. The study compared pilots who received a nap with those who stayed awake for the entire prolonged flight. The group that received a nap had improved reaction and response time based on the psychomotor vigilance test. Naps also improved the inadvertent lapses in alertness and microsleeps that occurred in pilots who did not nap. The results illustrate how naps can improve performance deficits that may occur from sleep deprivation. These improvements can also be augmented by the use of stimulants such as caffeine or light exposure. The combination of a 4-h prophylactic nap followed by 200 mg of caffeine at 1:30 a.m. and 7:30 a.m. resulted in significantly improved performance in continuous tasks. This improvement was superior to either napping or caffeine alone, suggesting an additive effect of these therapies. Another study evaluated the use of caffeine in addition to light exposure. The combination of 2500 lux bright light and caffeine significantly improved performance on vigilance tasks compared to using caffeine alone. These results suggest that caffeine or light exposure in addition to naps can have additive effects that improve symptoms of sleep loss.
Substances that Affect Fatigue or Sleepiness Many substances can have a significant effect on sleep and daytime hypersomnolence. Stimulants such as caffeine can improve alertness while sedatives such as alcohol can worsen somnolence. While many substances have a positive impact on the sleep–wake cycle, all can worsen daytime function when taken incorrectly.
Caffeine Caffeine is the most commonly ingested substance used to promote wakefulness and decrease somnolence (Table 3). Table 3
Caffeine content of commercial over-the-counter beverages
Beverage
Caffeine content (mg)
1 Coke 1 Mountain Dew 1 cup tea 1 Excedrin Extra Strength 1 cup Maxwell House Coffee 1 Starbucks Short
50 55 50 65 100 250
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Currently, studies suggest that the action of caffeine on alertness stems from inhibiting the production of adenosine. Adenosine builds up in the central nervous system during prolonged wake periods and follows a circadian rhythm pattern. Caffeine has been known to counteract this process. It is listed as a substance to avoid in the sleep hygiene rules due to effects on sleep onset. However, studies have evaluated the effects of caffeine on performance and alertness tests with sleep deprivation. After more than 50 h of sleep deprivation, patients who received at least 600 mg of caffeine showed significant improvements in mental activity compared to placebo. Compared to other stimulants such as dextroamphetamine or modafinil, caffeine tends to have a slightly decreased half-life and diminished effectiveness with prolonged sleep deprivation. However, it remains widely available as an over-thecounter drug or component of food. It is also much less expensive than other drugs. Therefore, it remains the first-line pharmacotherapy for restoring and maintaining cognitive performance and alertness during sleep loss. Shift workers, particularly night workers, can use caffeine as a means to maintain alertness if taken during their shift. The combination of caffeine and daytime naps can have additive effects to maintain cognitive function during a shift workers’ night.
Alcohol Alcohol has well-documented effects on decreasing alertness. In one study, ingestion of approximately 0.6 g kg 1 of alcohol decreased sleep latency on multiple sleep latency tests compared to placebo. Similar results were found in driving simulation studies where reduced sleep and ethanol ingestion resulted in significant impairment. Alcohol seems to decrease hand–eye coordination, response speed, and visual tracking. Subsequent sleep quality, total sleep time, sleep efficiency, and REM sleep also worsen with alcohol ingestion. Overall, avoiding alcohol intake remains an important practice in maintaining alertness in sleep-deprived individuals.
Nicotine Nicotine has unclear effects on sleep-deprived individuals. Studies evaluating nicotine infused intravenously after 48 h of sleep deprivation showed no significant impact on multiple sleep latency tests or psychomotor performance. However, several studies suggest that it may have some effects on sleep itself. Polysomnography was monitored for two pre-nicotine cessation nights and three post-cessation nights in 34 cigarette smokers. The results showed significantly worse objective and subjective measures of sleep quality. Moreover, patients who received nicotine replacement had improved sleep quality and fragmentation than those who did not receive replacement therapy. Another study showed increased reports of insomnia among individuals who had stopped smoking. This may be related to withdrawal effects from the nicotine. Unfortunately, these studies were limited to smokers, and larger samples in nonsmokers may be required before reaching conclusions about the effects of nicotine on sleep and sleep-deprived individuals.
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Medication Therapies Finally, various medications also seem to have a significant effect on sleep and daytime somnolence. Diuretics such as furosemide taken shortly before bedtime may worsen nocturia and lead to difficulties in sleep maintenance. Many sedatives used to treat insomnia often have long half-lives and may worsen alertness during the daytime, leaving a ‘hangover’ effect. Finally, stimulants such as caffeine, modafinil, or dextroamphetamine taken late in the day will delay sleep onset. Beta agonists or theophylline used in treating lung disease can cause significant anxiety and impair one’s ability to fall asleep. These medications should be dosed in the morning or early evening if absolutely required for nocturnal control of symptoms. While they are helpful in treating their respective symptoms, clinicians should be sure that patients understand the effects these drugs can have when taken at various times in the day.
Conclusion This article describes the currently available behavioral and environmental therapies studied to prevent and treat the effects of sleep loss. Therapies such as stimulants may offer significant short-term benefits while other measures such as posture, ambient temperature, bright light, and noise may produce less dramatic effects in sleep-deprived individuals. Full recovery from sleep deprivation eventually requires repaying the sleep debt. Good sleep hygiene, sleep restriction therapy, stimulus control therapy, and cognitive–behavioral therapy can all be useful treatments to assist in recovery. Many individuals struggle with the consequences of sleep deprivation on a regular basis; these effects can be difficult to treat. Pharmacotherapy, which will be discussed in another section, can be very effective but often brings potential side effects. Behavior and environmental countermeasures provide additional tools to individuals to combat their sleep deprivation with minimal side effects.
See also: Background: Concepts of Fatigue, Sleepiness, and Alertness; Critical Theoretical and Practical Issues: Eliminating Cumulative Sleep Debt and Sleep Satiation; Recovery from Sleep Loss; Role of Pharmacological Interventions for Sleep Deprivation; Healthy Sleep: Basic Sleep Tips; Creating an Optimal Sleep Environment; Optimal Sleep Habits in Middle-Aged Adults; Optimal Sleep Habits in the Elderly; Short-Term Countermeasures for Sleep Loss Effects: Naps.
Further Reading Akerstedt T and Torsvall L (1985) Napping in shift work. Sleep 8: 105–109. Baranski JV, Thompson MM, Lichacz FM, et al. (2007) Effects of sleep loss on team decision making: Motivational loss or motivational gain? Human Factors 49: 646–660. Bonnet MH and Arand DL (1994) The use of prophylactic naps and caffeine to maintain performance during a continuous operation. Ergonomics 37: 1009–1020.
Bonnet MH and Arand DL (1998) Sleepiness as measured by modified multiple sleep latency testing varies as a function of preceding activity. Sleep 21: 477–483. Bonnet MH and Arand DL (2005) Sleep latency testing as a time course measure of state arousal. Journal of Sleep Research 14: 387–392. Caldwell JA, Mallis MM, Caldwell JL, et al. (2009) Fatigue countermeasures in aviation. Aviation, Space, and Environmental Medicine 80: 29–59. Czeisler CA, Allan JS, Strogatz SH, et al. (1986) Bright light resets the human circadian pacemaker independent of the timing of the sleep-wake cycle. Science 233: 667–671. Freedman NS, Kotzer N, and Schwab RJ (1999) Patient perception of sleep quality and etiology of sleep disruption in the intensive care unit. American Journal of Respiratory and Critical Care Medicine 159: 1155–1162. Horne JA and Reid AJ (1985) Night-time sleep EEG changes following body heating in a warm bath. Electroencephalography and Clinical Neurophysiology 60: 154–157. Jorenby DE, Leischow SJ, Nides MA, et al. (1999) A controlled trial of sustained-release bupropion, a nicotine patch, or both for smoking cessation. New England Journal of Medicine 340: 685–691. Katz DA and McHorney CA (1998) Clinical correlates of insomnia in patients with chronic illness. Archives of Internal Medicine 158: 1099–1107. King AC, Oman RF, Brassington GS, et al. (1997) Moderate-intensity exercise and self-rated quality of sleep in older adults. A randomized controlled trial. Journal of the American Medical Association 277: 32–37. Krauchi K, Cajochen C, Werth E, et al. (1999) Warm feet promote the rapid onset of sleep. Nature 401: 36–37. Kripke DF, Simons RN, Garfinkel L, and Hammond EC (1979) Short and long sleep and sleeping pills. Is increased mortality associated? Archives of General Psychiatry 36: 103–116. Landolt HP, Dijk DJ, Gaus SE, et al. (1995) Caffeine reduces low-frequency delta activity in the human sleep EEG. Neuropsychopharmacology 12: 229–238. Landolt HP, Roth C, Dijk DJ, et al. (1996) Late-afternoon ethanol intake affects nocturnal sleep and the sleep EEG in middle-aged men. Journal of Clinical Psychopharmacology 16: 428–436. Landolt HP, Werth E, Borbely AA, et al. (1995) Caffeine intake (200 mg) in the morning affects human sleep and EEG power spectra at night. Brain Research 675: 67–74. Lubin A, Hord DJ, Tracy ML, and Johnson LC (1976) Effects of exercise, bedrest and napping on performance decrement during 40 hours. Psychophysiology 13: 334–339. Murphy PJ and Campbell SS (1997) Nighttime drop in body temperature: A physiological trigger for sleep onset? Sleep 20: 505–511. Poulton EC, Edwards RS, and Colquhoun WP (1974) The interaction of the loss of a night’s sleep with mild heat: Task variables. Ergonomics 17: 59–73. Reyner LA and Horne JA (1998) Evaluation ‘in-car’ countermeasures to sleepiness: Cold air and radio. Sleep 21: 46–50. Roehrs T, Zwyghuizen-Doorenbos A, and Roth T (1993) Sedative effects and plasma concentrations following single doses of triazolam, diphenhydramine, ethanol and placebo. Sleep 16: 301–305. Rosekind MR, Smith RM, Miller DL, et al. (1995) Alertness management: Strategic naps in operational settings. Journal of Sleep Research 4: 62–66. Strogatz SH, Kronauer RE, and Czeisler CA (1987) Circadian pacemaker interferes with sleep onset at specific times each day: Role in insomnia. American Journal of Physiology 253: R172–R178. Vgontzas AN, Liao D, Pejovic S, et al. (2010) Insomnia with short sleep duration and mortality: The Penn State cohort. Sleep 33: 1159–1164. Werth E, Dijk DJ, Achermann P, et al. (1996) Dynamics of the sleep EEG after an early evening nap: Experimental data and simulations. American Journal of Physiology 271: R501–R510. Wetter DW, Fiore MC, Baker TB, et al. (1995) Tobacco withdrawal and nicotine replacement influence objective measures of sleep. Journal of Consulting and Clinical Psychology 63: 658–667. Wright KP Jr., Badia P, Myers BL, and Plenzler SC (1997) Combination of bright light and caffeine as a countermeasure for impaired alertness and performance during extended sleep deprivation. Journal of Sleep Research 6: 26–35. Yokoi M, Aoki K, Shimomura Y, Iwanaga K, and Katsuura T (2006) Exposure to bright light modifies HRV responses to mental tasks during nocturnal sleep deprivation. Journal of Physiological Anthropology 25: 153–161. Youngstedt SD, O’Connor PJ, and Dishman RK (1997) The effects of acute exercise on sleep: A quantitative synthesis. Sleep 20: 203–214.
Contents Behavioral and Environmental Countermeasures of Sleep Loss Naps
Behavioral and Environmental Countermeasures of Sleep Loss C Poon and K A Hardin, University of California, Sacramento, CA, USA ã 2013 Elsevier Inc. All rights reserved.
Glossary Cognitive–behavioral therapy: A form of treatment that utilizes different behaviors and environmental factors to alter unhealthy thinking patterns and associated behaviors. Phase advance: A condition in which sleep begins and ends earlier than the desired time for sleep. Phase delay: A condition in which sleep begins and ends later than the desired time for sleep. Sleep architecture: The structure and pattern of sleep which can be divided into different sleep stages differentiated by brain activity on an electroencephalogram. Sleep debt: A condition where the quantity of sleep is insufficient to support the normal alertness, performance, or health of an individual.
Introduction Sleep deprivation is an extremely common problem in the United States affecting 10–20% of the population. Studies by the National Sleep Foundation show that approximately 20% of Americans report sleeping 6.5 h or less per night. Populations at high risk for sleep loss include shift workers such as airplane pilots, the elderly, and individuals with psychological, medical, or pain syndromes. Both acute and chronic sleep loss can lead to physical, mental, and even psychological impairment. The full impact of fatigue is often underappreciated, but many of its effects have long been known. The most significant symptom associated with sleep deprivation is hypersomnolence. Hypersomnolence can have a significant impact on behavioral characteristics, such as cognitive performance, reaction time, attention, and alertness. Compared to people who are well-rested, individuals who are sleep-deprived think and move more slowly, make more mistakes, and have memory difficulties. A significant increase in accidents occurs in people who report less than 7 h of sleep per night. After a single night of inadequate sleep (< 5 h), driving performance significantly decreases, and
Encyclopedia of Sleep
http://dx.doi.org/10.1016/B978-0-12-378610-4.00075-9
Sleep deprivation: The condition of not having adequate sleep quantity or quality. Sleep homeostasis: The constant, finely regulated balance of sleep duration and intensity. Sleep hygiene: Sleep habits; good sleep hygiene practices include setting standardized bedtime and awakening times, avoiding reading or watching television in bed, avoiding naps, and remaining in bed only when sleepy. Sleep latency: The time from lights out to sleep onset. White noise: A type of noise produced by combining sounds of all frequencies together. Because it contains all frequencies, it often masks specific sounds making them indistinguishable.
unfortunately, most drivers underestimate their impairment. As a result, excessive sleepiness is one of the leading causes of automobile crashes and major professional trucking crashes in the United States. Individuals with chronic sleep loss also have higher incidences of stomach problems, such as heartburn and indigestion, infections, weight gain, and cardiovascular problems. Mortality has been shown to increase in individuals who chronically sleep less than 5 h per night. Given the profound consequences associated with sleep deprivation, countermeasures are needed to prevent sleep loss and combat its associated symptoms. This article will review the behavioral and environmental factors to prevent and counteract the effects of sleep loss. Details of chronic sleep deprivation, prevention, and treatment are discussed in other articles (Table 1).
Countermeasures to Prevent Sleep Loss Recurrent sleep loss of even small amounts will eventually perpetuate a state of chronic sleep deprivation. Therefore,
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Short-Term Countermeasures for Sleep Loss Effects | Behavioral and Environmental Countermeasures of Sleep Loss
Table 1
Summary of behavior countermeasures for sleep loss
Strategy
Description
Sleep hygiene
Habits and behaviors that promote effective sleep onset and maintenance Method used to prevent the association between the bedroom and increased wakefulness Technique that sets a specific schedule of being in bed in order to improve the homeostatic drive to fall asleep A technique that uses a combination of behaviors and environmental factors to remove unhealthy thoughts and beliefs about one’s ability to fall asleep Methods including muscle relaxation, biofeedback, and guided imagery to reduce stress in preparation for sleep Using activities such as a 5-min walk or standing in order to temporarily increase alertness The use of short 5–20-min breaks to improve cognitive function in continuous tasks Cool temperature can be used to improve alertness in limited studies Bright light regulates the circadian rhythm and can be used to improve alertness, especially in shift workers at night Loud noise can decrease somnolence in sleep-deprived individuals Short naps can temporarily improve alertness that results from prolonged sleep deprivation
Stimulus control Sleep restriction
Cognitive– behavioral therapy Relaxation therapy
Activity Rest breaks Temperature Light
Noise Naps
Table 2
• • • • • • • • • •
Sleep hygiene rules
Sleep only as much as needed and then get out of bed Keep a regular sleep schedule Exercise regularly but at least 4–5 h before bedtime Avoid caffeine after lunch Avoid alcohol near bedtime Avoid smoking Do not go to bed hungry Adjust bedroom environment to decrease stimuli Resolve your worries before bedtime Avoid forcing sleep
returning to a normal sleep schedule as soon as possible remains an important part of recovery. Behavior and environmental factors can be useful in helping individuals return to a regular, rejuvenating sleep schedule.
Sleep Hygiene There are many factors that can cause sleep loss, such as change in environment associated with traveling, bedtime habits, shift work, and military action. After a prolonged period, patients eventually need to recover from their sleep debt. Practicing good sleep hygiene remains an important part of recovery. It also helps to prepare individuals expecting to enter a period of sleep deprivation. The term refers to behaviors which improve quantity and quality of sleep. Originally, it was used by Peter Hauri and colleagues to improve symptoms of insomnia in 1977. These rules were primarily derived by observing
common practices of patients with poor sleep. Although these recommendations have evolved since their original description, they still aim to avoid behaviors that interfere with normal sleep and encourage behaviors that promote good sleep (Table 2).
Stimulus Control When people are exposed to a different or changing environment, they often have difficulty falling or staying asleep. Temporary and long-term techniques can be used to prevent the psychological association between bedtime and staying awake. Stimulus control therapy tries to separate the association between going to bed and increased arousal. Spending time awake in bed strengthens the association between wakefulness and the bedroom. The longer one stays in bed trying to sleep, the stronger the association becomes. This perpetuates difficulty falling asleep. The goal of stimulus control is to increase the likelihood of sleep by disrupting the association between the bedroom and wakefulness. Patients should go to bed only when drowsy and ready to sleep. The bedroom should not be used for other activities such as reading, watching television, or eating. If a patient has difficulty falling asleep while in bed for a prolonged period, he or she should get out of bed, engage in a relaxing activity, and return only when sleepy. The process is repeated if the patient still cannot sleep for more than 20 min. An alarm clock should be set to wake the patient at the same time every morning to encourage a steady sleep schedule. Many studies have found stimulus control to be effective in promoting effective sleep. It has been most successful in improving sleep onset and sleep maintenance.
Sleep Restriction Many patients have difficulty falling asleep and stay in bed for prolonged periods. Their wake and bedtimes often occur at irregular times. This results in shifts of the normal circadian system and increased somnolence at inappropriate times. Sleep restriction therapy, similar to stimulus control, attempts to limit the amount of time patients spend in bed but provides a daily schedule to follow for going to bed and waking. The process begins by keeping a sleep diary to document the patient’s usual amount of sleep. The patient then decreases the amount of time in bed to the amount of sleep reported in these diaries. A consistent wake time is also scheduled. As patients spend less time in bed, there is an increase in the normal homeostatic drive to sleep. Bedtime is then advanced earlier until the desired schedule is achieved. Any worsening of sleep efficiency results in a later bedtime. Eventually, patients become accustomed to going to bed and falling asleep quickly. One disadvantage of this technique is increased daytime somnolence during the initial phase of treatment. Many patients also resist the idea of going to bed later since it reduces their available time to obtain sleep. It is best to start the sleep restriction process when the patient has several days to acclimatize, such as the weekend away from the work environment. This will decrease the stress related to the initial decrease in daytime functioning due to hypersomnolence.
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A study with 21 elderly patients compared sleep hygiene alone with combined sleep restriction and sleep hygiene. Patients in the sleep restriction group obtained a significantly greater increase in sleep efficiency, self-reported mood on awakening, and sleep continuity. The results indicated that sleep restriction therapy had a very sustainable effect 1 year later.
Cognitive Behavioral Therapy Combating sleep loss symptoms requires understanding factors that may influence delayed sleep onset. Some classic hallmarks of difficulty falling asleep include irrational fears, unrealistic expectations, and excessive worrying about sleep. Patients with these difficulties may be preoccupied with the thought of falling asleep. They worry about daytime impairments in their occupation and health because of sleep deprivation. These fears place pressure on an individual to fall asleep. Cognitive therapy challenges these beliefs and fears in order to restructure an individual’s negative outlook. As a result, the anxiety associated with sleep at bedtime decreases. Cognitive behavioral therapy combines cognitive therapy with the previously mentioned nonpharmacologic therapies such as sleep restriction, sleep hygiene, and stimulus control. Additionally, reasons and consequences of the patients’ thoughts and concerns regarding impairment to their sleep are addressed in weekly sessions. The goal of this combined therapy is to simultaneously change the abnormal sleep habits and cognitive outlook of sleep. A sample program may begin with a session focusing on stimulus control and sleep restriction. The next session may teach proper sleep hygiene and cognitive therapy. The course ends with a session that integrates the other lessons and addresses potential problems in maintenance of a proper sleep schedule. These sessions have shown lasting improvements on sleep onset and maintenance. This occurs by forming habits in individuals that encourage sleep. In addition, this approach offers treatment for patients such as older adults, pregnant women, or patients with specific medical illnesses who cannot take sedative medications. Unfortunately, few clinicians have been formally trained to provide cognitive behavioral therapy, and its benefits may be reduced when administered by less experienced individuals. Despite prolonged use, cognitive behavioral therapy does not seem to have significant adverse long-term effects.
Relaxation Therapy Individuals who have significant psychological or physical stress will also have difficulties recovering from sleep deprivation. Relaxation therapy attempts to improve hyperarousal in order to allow adequate sleep. There are several techniques described to achieve this goal including progressive muscle relaxation, biofeedback, and guided imagery. Progressive muscle relaxation was initially developed by Edmund Jacobsen in the 1930s. It was specifically applied to treat difficulties sleeping. The patient is instructed to tense and then systematically relax various areas of the body. Eventually the whole body is relaxed. Several studies suggest a positive impact on sleep. At least one trial involving 57 patients with sleep deprivation treated with progressive relaxation therapy showed improved sleep onset. Other limited studies show improvements in different sleep parameters.
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Biofeedback teaches relaxation by providing patients with a signal that measures their level of stress. Usually this technique employs electroencephalogram (EEG) or electromyogram (EMG) to signal an increase in tension. In a typical session, the patient will learn how to better relax by focusing on their feedback signal when it shows an increase in stress. This technique, however, is not commonly used, partly due to its duration and intensity. Often, patients may also require between 30 and 90 sessions to successfully master this form of relaxation. Guided imagery involves having a patient imagine and meditate on a relaxing scene. Scenes commonly used include lying on a beach, taking a hot bath, or sitting in front of a warm fire. When a patient becomes efficient at this task, they can induce relaxation quickly by focusing on the visual image. This relaxation therapy technique is helpful in patients with increased cognitive arousal since it offers a distraction from their usual worries. Each of these therapies improves the hyperarousal state that prevents individuals from going to sleep. While many articles and studies suggest that these treatments provide a benefit, additional studies on their efficacy are still needed.
Countermeasures to Combat the Effects of Sleep Loss If adequate sleep cannot be obtained, various measures can be used to prevent or minimize the effect of sleep loss. Upon discovering signs of diminishing performance and somnolence, individuals can use activity, environmental factors, or even stimulants to temporarily improve their alertness. Unfortunately, sleep is a biological need and sheer determination or willpower cannot offset the mounting effects of inadequate sleep.
Activity In early sleep deprivation, brief periods of activity can temporarily improve somnolence. Sleep latency tests have been widely used to illustrate this concept. For example, in one study, 18 healthy subjects underwent five sleep latency tests after two nights of sleep deprivation. One of these tests was performed after a 5-min walk. The test was repeated on 2 separate weeks. The results showed a significant increase in sleep latency after the 5-min walk. Heart rate also increased shortly after activity, suggesting increased arousal. The study illustrates that short periods of activity such as a 5-min walk can temporarily reverse the effects of hypersomnolence. Another study evaluated 14 normal young adults with maintenance of wakefulness tests after being awake for 7, 19, and 31 h. During these tests, subjects were required to do various activities such as standing, performing knee bends, or quietly listening to someone talking. Wakefulness improved significantly while subjects were standing and performing knee bends compared to listening to someone talking. This improvement diminished over longer wake periods. As a result, the benefits of activity may only be effective with early or milder sleep loss. In addition, prolonged activity may actually worsen fatigue over time.
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Rest Periods Short breaks can increase alertness by reducing the conscious disengagement of monotonous tasks. Although not as effective as other countermeasures, brief periods of rest from a continuous task can serve to acutely improve alertness and performance. A recently published study evaluated the effects of total break time on individuals performing data entry. Four 5-min supplemental breaks were added to the two standard 15-min breaks in a workday. After 4 weeks, the workers who received an additional 20 min of break time per day had significantly faster data entry speeds without loss of productivity. There were also reductions in reports of physical discomfort. Breaks can also have a positive impact on individuals experiencing partial or total sleep loss. At least two separate protocols have studied subjects who had 54 and 64 h of continuous wake time. Individuals who received five 20-min rest breaks during required tasks showed improvements in performance, alertness, fatigue, and mood compared to those who received no breaks. These data have been useful in the schedules of military pilots where breaks have been used to overcome somnolence and fatigue in sustained operations. However, these improvements in performance may not occur in all situations. One study evaluating industrial engineers found that mishaps occurred more frequently with 15-min breaks every 2 h. The study suggests that improvements in performance with rest breaks should take into account the nature of the task itself.
Temperature Another factor that affects sleep onset is temperature. Typically, temperature follows a diurnal pattern that decreases during periods of energy conservation. Core body temperature decreases in the late evening usually reaching a nadir at approximately 2 a.m. and is associated with an increase in homeostatic need for sleep. This decrease in core body temperature is not limited by circadian rhythm, however, since temperature also decreases during naps. Many studies have evaluated whether adjustments in core or distal body temperature can affect sleep onset. ‘Passive body heating’ through the use of hot baths has shown improvements in the depth and quality of subsequent sleep. These studies were performed in both normal sleepers and older adults. Distal body temperature warming relative to core body temperature seems to have the most profound effect on sleep onset. Patients with sleep onset insomnia also have improved sleep onset with mild warming of their distal extremities. Because adjustments in body temperature seem to affect the onset of sleep, several studies have looked at temperature as a way to improve wakefulness. Unfortunately, a consistent benefit has not been shown during sleep loss. One study required 16 young adult drivers to drive an interactive car simulator for 2.5 h with the air conditioner blowing cold air in their face during the afternoon after they had received only 5 h of sleep the previous night. They were evaluated for ‘incidents’ of drifting over lane markings when compared to a group who did not drive with the air conditioner. The study did not show a significant difference between total numbers of mistakes.
However, there was a trend toward fewer ‘incidents’ with both radio and cool air during the first 30 min of driving. Another study did show that heat up to 92 F was effective in improving performance during vigilance tasks after sleep deprivation. Results suggest that changes in ambient temperature may have some effect on the symptoms of sleep deprivation. However, further studies would be required to further evaluate these findings.
Light Bright light can be a source of stimulation. Studies show that the circadian rhythm adjusts to the surrounding light–dark schedule. Light exposure during the habitual night shifts sleep onset later (phase delay) while exposure in the early morning can cause it to shift earlier (phase advance). From these observations, light may act as a source of stimulation to prevent the effects of acute sleep loss. One study evaluated the effect of bright light compared to dim light on patients required to do repetitive mental tasks. Those patients who were exposed to bright light had delayed heart rate decline that normally accompanies sleep onset. There was also less heart rate variability during repetitive mental tasks. The study suggests that bright light exposure delays the nocturnal decrease in heart rate and maintains autonomic balance needed for mental tasks. It also illustrates how bright light can delay the physiologic changes that accompany sleep onset. A recent review of the literature also concluded that light may exert an alerting effect in the evenings. These alerting effects may be tied to suppression of melatonin, which is normally released in the mid to late night. Light therefore has the potential to slow decline in performance and alertness that often occurs prior to falling asleep. Some evidence also suggests that these alerting effects are independent of the time of day. If true, it suggests that light may be an effective therapy to improve alertness and performance impairment from sleep loss.
Noise Individuals who try to sleep usually benefit from a quiet environment away from intermittent noises and disruptions. Sudden loud noises become more disruptive to sleep than continuous noises. In fact, monotonic noises such as the sound of a fan, also known as white noise, can be helpful in masking environmental stimuli. Earplugs can also be used to block excess noise and promote sleep onset. Counterintuitively, loud noise may have a beneficial effect on hypersomnolence during sleep deprivation. Although performance often worsens in well-rested individuals, loud, stimulating noise may temporarily improve the effects from sleep deprivation. Noise levels below 40 decibels are required for a normal individual to fall asleep. As a reference, a busy office has an average noise level of 70 dB. The front-row seats of a rock concert may have a noise level of 110 dB. Any increase in noise intensity can cause arousals from sleep. Some studies show that exposure to noise levels found in a hospital intensive care unit results in a decrease in total sleep time, total rapid eye movement (REM) sleep, sleep efficiency, REM sleep latency,
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and number of arousals. However, large studies still need to be performed to fully characterize the effects of noise on sleep loss.
Naps A full review of naps will be discussed in a separate chapter. Briefly, naps are a very effective nonpharmacological technique for restoring alertness. Several studies have documented how naps taken during long periods of continuous wakefulness can be extremely beneficial. For example, airplane pilots who take an average of a 26-min nap during a prolonged flight showed significant improvement in subsequent alertness and psychomotor performance. The study compared pilots who received a nap with those who stayed awake for the entire prolonged flight. The group that received a nap had improved reaction and response time based on the psychomotor vigilance test. Naps also improved the inadvertent lapses in alertness and microsleeps that occurred in pilots who did not nap. The results illustrate how naps can improve performance deficits that may occur from sleep deprivation. These improvements can also be augmented by the use of stimulants such as caffeine or light exposure. The combination of a 4-h prophylactic nap followed by 200 mg of caffeine at 1:30 a.m. and 7:30 a.m. resulted in significantly improved performance in continuous tasks. This improvement was superior to either napping or caffeine alone, suggesting an additive effect of these therapies. Another study evaluated the use of caffeine in addition to light exposure. The combination of 2500 lux bright light and caffeine significantly improved performance on vigilance tasks compared to using caffeine alone. These results suggest that caffeine or light exposure in addition to naps can have additive effects that improve symptoms of sleep loss.
Substances that Affect Fatigue or Sleepiness Many substances can have a significant effect on sleep and daytime hypersomnolence. Stimulants such as caffeine can improve alertness while sedatives such as alcohol can worsen somnolence. While many substances have a positive impact on the sleep–wake cycle, all can worsen daytime function when taken incorrectly.
Caffeine Caffeine is the most commonly ingested substance used to promote wakefulness and decrease somnolence (Table 3). Table 3
Caffeine content of commercial over-the-counter beverages
Beverage
Caffeine content (mg)
1 Coke 1 Mountain Dew 1 cup tea 1 Excedrin Extra Strength 1 cup Maxwell House Coffee 1 Starbucks Short
50 55 50 65 100 250
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Currently, studies suggest that the action of caffeine on alertness stems from inhibiting the production of adenosine. Adenosine builds up in the central nervous system during prolonged wake periods and follows a circadian rhythm pattern. Caffeine has been known to counteract this process. It is listed as a substance to avoid in the sleep hygiene rules due to effects on sleep onset. However, studies have evaluated the effects of caffeine on performance and alertness tests with sleep deprivation. After more than 50 h of sleep deprivation, patients who received at least 600 mg of caffeine showed significant improvements in mental activity compared to placebo. Compared to other stimulants such as dextroamphetamine or modafinil, caffeine tends to have a slightly decreased half-life and diminished effectiveness with prolonged sleep deprivation. However, it remains widely available as an over-thecounter drug or component of food. It is also much less expensive than other drugs. Therefore, it remains the first-line pharmacotherapy for restoring and maintaining cognitive performance and alertness during sleep loss. Shift workers, particularly night workers, can use caffeine as a means to maintain alertness if taken during their shift. The combination of caffeine and daytime naps can have additive effects to maintain cognitive function during a shift workers’ night.
Alcohol Alcohol has well-documented effects on decreasing alertness. In one study, ingestion of approximately 0.6 g kg 1 of alcohol decreased sleep latency on multiple sleep latency tests compared to placebo. Similar results were found in driving simulation studies where reduced sleep and ethanol ingestion resulted in significant impairment. Alcohol seems to decrease hand–eye coordination, response speed, and visual tracking. Subsequent sleep quality, total sleep time, sleep efficiency, and REM sleep also worsen with alcohol ingestion. Overall, avoiding alcohol intake remains an important practice in maintaining alertness in sleep-deprived individuals.
Nicotine Nicotine has unclear effects on sleep-deprived individuals. Studies evaluating nicotine infused intravenously after 48 h of sleep deprivation showed no significant impact on multiple sleep latency tests or psychomotor performance. However, several studies suggest that it may have some effects on sleep itself. Polysomnography was monitored for two pre-nicotine cessation nights and three post-cessation nights in 34 cigarette smokers. The results showed significantly worse objective and subjective measures of sleep quality. Moreover, patients who received nicotine replacement had improved sleep quality and fragmentation than those who did not receive replacement therapy. Another study showed increased reports of insomnia among individuals who had stopped smoking. This may be related to withdrawal effects from the nicotine. Unfortunately, these studies were limited to smokers, and larger samples in nonsmokers may be required before reaching conclusions about the effects of nicotine on sleep and sleep-deprived individuals.
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Medication Therapies Finally, various medications also seem to have a significant effect on sleep and daytime somnolence. Diuretics such as furosemide taken shortly before bedtime may worsen nocturia and lead to difficulties in sleep maintenance. Many sedatives used to treat insomnia often have long half-lives and may worsen alertness during the daytime, leaving a ‘hangover’ effect. Finally, stimulants such as caffeine, modafinil, or dextroamphetamine taken late in the day will delay sleep onset. Beta agonists or theophylline used in treating lung disease can cause significant anxiety and impair one’s ability to fall asleep. These medications should be dosed in the morning or early evening if absolutely required for nocturnal control of symptoms. While they are helpful in treating their respective symptoms, clinicians should be sure that patients understand the effects these drugs can have when taken at various times in the day.
Conclusion This article describes the currently available behavioral and environmental therapies studied to prevent and treat the effects of sleep loss. Therapies such as stimulants may offer significant short-term benefits while other measures such as posture, ambient temperature, bright light, and noise may produce less dramatic effects in sleep-deprived individuals. Full recovery from sleep deprivation eventually requires repaying the sleep debt. Good sleep hygiene, sleep restriction therapy, stimulus control therapy, and cognitive–behavioral therapy can all be useful treatments to assist in recovery. Many individuals struggle with the consequences of sleep deprivation on a regular basis; these effects can be difficult to treat. Pharmacotherapy, which will be discussed in another section, can be very effective but often brings potential side effects. Behavior and environmental countermeasures provide additional tools to individuals to combat their sleep deprivation with minimal side effects.
See also: Background: Concepts of Fatigue, Sleepiness, and Alertness; Critical Theoretical and Practical Issues: Eliminating Cumulative Sleep Debt and Sleep Satiation; Recovery from Sleep Loss; Role of Pharmacological Interventions for Sleep Deprivation; Healthy Sleep: Basic Sleep Tips; Creating an Optimal Sleep Environment; Optimal Sleep Habits in Middle-Aged Adults; Optimal Sleep Habits in the Elderly; Short-Term Countermeasures for Sleep Loss Effects: Naps.
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