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Sleep difficulties are widespread across cultures and becoming more prevalent. The impact of sleep disorders and other sleep problems is significant in both personal and economic cost. Insomnia alone costs $63.2 billion in lost productivity in the United States every year. The need for simple, easy-to-implement treatments is growing, leading to the popularity of what’s called “good sleep hygiene.”
Note: The content on Sleepopolis is meant to be informative in nature, but it shouldn’t take the place of medical advice and supervision from a trained professional. If you feel you may be suffering from any sleep disorder or medical condition, please see your healthcare provider immediately.
What is Sleep Hygiene?
Sleep hygiene is a set of habits and practices associated with sleep, the sleeping environment, and the bedtime routine. Sleep hygiene recommendations are intended to help improve the quality and duration of sleep. They were originally developed to relieve mild to moderate insomnia symptoms, though the term has since become a catch-all phrase for a variety of behaviors that promote healthy sleep.
HygieneConditions or practices conducive to maintaining health and preventing disease.
The term “sleep hygiene” was first used in 1939, but became part of the lexicon of modern sleep medicine in 1977 when psychologist Peter Hauri described a list of simple actions intended to improve sleep. The typical sleep hygiene checklist includes the following recommendations:
- Go to bed and wake up at consistent times, even on weekends
- Create a quiet, dark, and cool sleeping environment
- Avoid eating meals or drinking caffeine or alcohol in the hours before bedtime
- Reduce or eliminate naps
- Turn off sources of blue light, including computers, smartphones, televisions, and tablets, at least one hour before bed
Other common suggestions include reserving the bed for sleep and sex only, and exercising regularly but not too close to bedtime. Though these tips are intended to improve sleep and even eliminate insomnia, many sleep hygiene lists don’t prioritize recommendations, describe how to practice good sleep hygiene, or explain how the suggestions prevent or treat persistent insomnia.
What’s the science behind these suggestions? When put into practice, do they help to improve sleep patterns and sleep disorders such as insomnia?
The Research Behind Sleep Hygiene
Sleep hygiene suggestions may appear to make good sense, and for people struggling to establish healthy sleep habits, they could be helpful. Their usefulness as a treatment for insomnia and sleep disorders is less clear.
InsomniaDifficulty falling asleep, staying asleep, or falling back to sleep. Insomnia symptoms lasting three months or longer are considered chronic insomnia, or insomnia disorder.
There are few research studies supporting sleep hygiene as a remedy for chronic sleep difficulties. Though some studies reference good sleep hygiene as an adjunct to such treatments as cognitive behavioral therapy for insomnia, recent science does not support sleep hygiene as a sufficient treatment for insomnia or other sleep disorders.
Despite the dearth of research studies, sleep hygiene recommendations have become ubiquitous. Sleep hygiene resources are available in books and across the internet, including public websites from such institutions as the Division of Sleep Medicine at Harvard Medical School. Inadequate sleep hygiene was included as a cause of insomnia in The International Classification of Sleep Disorders manual in 1990, but has since been removed due to a lack of reproducible studies. (1)
Though the American Academy of Sleep Medicine includes references to sleep hygiene in their updated guidelines, they do not suggest sleep hygiene as a treatment for chronic insomnia, citing lack of scientific evidence. (2) Examined as individual recommendations, some sleep hygiene suggestions have more evidence as treatment for difficulty falling or staying asleep than others.
Consistent Sleep and Wake Times
Consistency in sleep habits may be one of the most scientifically supported sleep hygiene recommendations. (3) Inconsistent sleep and wake times may include frequent or long naps during the day, shift work, and frequent travel across time zones.
The circadian rhythm is highly sensitive to environmental cues, including light and darkness, meal times, and the sleeping environment. Going to bed and waking up at inconsistent times can disrupt the circadian rhythm, leading to daytime sleepiness, irritability, and insomnia symptoms such as difficulty falling asleep and staying asleep.
Even a single night of inconsistent sleep can cause decreased cognitive functioning on laboratory tests. (4) Most sleep specialists recommend going to bed and waking up at consistent times during the week and on weekends. Consistency in waking routines, including meal and work times and going outside, appears to help sleep, as well. (5)
Consistency helps to align the circadian rhythm of sleep with that of other circadian-influenced functions, such as digestion, hormone release, and body temperature. (6) The rhythm of these varied physical processes may help explain why insufficient sleep has such a significant negative impact on metabolism, cognitive functioning, and cardiovascular health. Consistency in sleep is also associated with lower body fat in women, as well as better mental health. (7) A consistent sleep schedule may also reduce the time it takes to fall asleep, a process known as sleep latency.
Avoiding Use of Electronic Devices Before Bed
One of the most common sleep hygiene suggestions is to turn off electronic devices such as smartphones, tablets, and televisions before bed. The blue light emitted by these devices may impact the circadian rhythm in a similar way to sunlight, delaying or preventing sleep. (8)
Blue light is one of the colors in the visible light spectrum, meaning it is detectable by the human eye. There is an inverse relationship between the wavelengths of light and the energy it emits. Blue light has a short wavelength and emits more energy than light with a longer wavelength.
During the day, blue light benefits mood and helps to keep us alert. Blue light also has a positive effect on cognitive function, and helps to improve reaction times. Sunlight is the main source of blue light, which scatters easily when it strikes air and water molecules in the atmosphere.
FAQQ: Why does the sky appear blue? A: The scattering of blue light in the atmosphere causes the sky to look blue instead of other colors on the spectrum, which scatter less easily.
Nearly all of the blue light we see from sunlight and electronic devices reaches the retina of the eye, which sends light and darkness signals to the brain. The circadian rhythm depends on these signals to help regulate sleep and wake times, as well as hormone release, hunger and satiety, and metabolism.
Many sleep scientists believe that, while blue light during the day is beneficial to health, the body and brain weren’t designed for blue light exposure after sunset. Glasses intended to filter out blue light from electronics have become more popular, though science supporting their effectiveness is scarce.
Blue light may come from the following artificial sources:
- Reading devices
- LED lights
- Video games
While the evidence of harm to the eye from exposure to artificial blue light is inconclusive, the American Academy of Ophthalmology believes that blue light can interrupt the circadian rhythm and disturb sleep. (9) As a sleep hygiene recommendation, avoidance of blue light within a few hours of bed appears to have sound scientific support.
A Cool, Dark, Quiet Sleeping Environment
Certain aspects of the sleeping environment can have a significant effect on sleep. Core body temperature decreases just before and during sleep, while darkness helps promote release of melatonin. A quiet bedroom helps maintain sensory gating, which is the brain’s way of filtering out non-threatening stimuli and protecting sleep.
The body prepares for sleep by lowering core temperature. (10) Core temperature is measured in deeper parts of the body such as the blood and vital organs. Core temperature begins to drop in the late afternoon and gradually decreases over the course of the evening. (11) Core temperature falls further after sleep begins, while skin temperature remains steady.
A cool bedroom may help keep core body temperatures constant and promote healthy sleep. (12) The body’s ability to regulate its internal temperature — called thermoregulation — is reduced during sleep. Because sweating and shivering decrease significantly, the body may respond to an excessively warm environment by waking up to cool itself. The need to maintain a stable temperature may lead to delayed or disrupted sleep.
MelatoninA sleep-promoting hormone produced by the pineal gland in the brain. Melatonin helps to regulate sleep and wake cycles, and can be taken in supplement form.
The circadian rhythm is strongly influenced by light and darkness signals. Even small amounts of artificial or natural light can send wake signals to the brain and reduce or stop the release of melatonin. Reducing the use of all lights at night, particularly those that emit blue light such as LED lights and electronic devices, may help promote sleep and reduce the time it takes to fall asleep.
Noise from any source can disturb sleep, particularly when inconsistent or reverberating. (13) Studies show that time spent in deep sleep increases in a quiet environment, while awakenings increase in a noisy one. Though certain types of brain waves help to protect the brain from waking in the deeper stages of sleep through sensory gating, noise or other sensory stimuli can easily awake a sleeper in the lighter N1 and REM stages of sleep.
Abstaining From Food, Alcohol, and Caffeine Before Bed
Eating a meal before bed — or eating at all — is typically discouraged by proponents of good sleep hygiene. Studies are mixed, with some suggesting that pre-bedtime meals have the effect of waking up the digestive system, disrupting the circadian rhythm, and increasing body fat.(14)
Other research shows that small, nutrient-dense meals may help promote healthy sleep and prevent sleep difficulties due to hunger. Eating foods high in protein could even help boost metabolism and burn more calories. (15) Small amounts of protein-rich foods may offer nutrition to muscles and other tissues that undergo repair processes during sleep.
Most studies about metabolism and sleep support not eating in the few hours before bed, or eating only lightly. While healthy sleep may not require fasting altogether, large meals can interrupt sleep patterns, cause heartburn, and stimulate organs that would otherwise be less active. (16)
Avoiding alcohol and caffeine are other common sleep hygiene suggestions. Caffeine is a stimulant that blocks receptors for adenosine, a neurotransmitter that causes sleepiness as levels rise over the course of a day. Caffeine can delay or prevent sleep even if consumed only in the morning, but can be particularly disruptive to sleep if consumed closer to bedtime.
FAQQ: How much caffeine does the average person consume? A: Caffeine is the most popular drug in the US. More than half of Americans consume at least 300 milligrams a day, or the equivalent of three cups of coffee.
Research supports the recommendation to avoid caffeine close to bedtime. (17) Though caffeine can help combat feelings of fatigue, it may contribute to these feelings by interrupting the sleep-wake cycle and further increasing the need for stimulants to stay alert. Caffeine can lower sleep quality, and create a state of physical withdrawal during sleep that results in lowered mood and morning sleepiness.
Studies strongly support the assertion by proponents of sleep hygiene that alcohol can cause sleep difficulties. Although alcohol is a nervous system depressant and not a stimulant, its effects on sleep can be as disruptive as those experienced by some caffeine users.
Alcohol can help healthy, non-alcoholic users fall asleep more quickly, but makes awakenings during the night more likely. This may be due to the effect of alcohol “wearing off” during sleep, causing rebound wakefulness. Alcohol also hampers the circadian rhythm’s ability to synchronize the master clock with other smaller “local” clocks in organs and muscle tissue. This can lead to compromised liver and gastrointestinal function as well as sleep disruption. (18)
Alcohol suppresses REM sleep, which may impact overall sleep quality as well as the cognitive and physical processes that take place during REM, such as dreaming and memory consolidation. In addition, alcohol reduces the production of melatonin and changes the pattern of sleep stages, also known as sleep architecture. (19)
Memory consolidationThe cognitive process of stabilizing certain memories after they've been acquired by the brain.
Alcohol leads to greater than normal relaxation of the head and neck, increasing the risk of sleep-related breathing disorders such as sleep apnea. (20) It may also cause or worsen insomnia, snoring, and parasomnia disorders such as sleepwalking.
Reducing the frequency of naps is a common suggestion on sleep hygiene lists. Many sleep specialists advise patients struggling with insomnia and other sleep disturbances to cut out naps to help increase the drive to sleep and improve sleep efficiency.
Though brief naps may help to restore alertness and diminish the feeling of sleepiness in people who are considered “good sleepers,” numerous studies demonstrate that daytime sleeping can reduce or disrupt the homeostatic drive to sleep at night. For that reason, specialists in insomnia treatment often recommend foregoing naps to help regulate the circadian rhythm and sleep-wake cycles. Not napping is part of the protocol of sleep restriction, a type of therapy used for chronic insomnia. (21)
What Works for Chronic Insomnia?
While most sleep hygiene suggestions are supported by science, they don’t appear to be sufficient in themselves to treat persistent sleep disorders such as chronic insomnia. This may be in part because most people suffering from insomnia disorder try to alleviate their symptoms early on with relatively simple sleep hygiene suggestions, which are often ineffective. More rigorous research is needed to understand the role of sleep hygiene in the treatment of sleep difficulties and disorders. (22)
Chronic insomnia is generally not a result of poor sleep hygiene, but a disorder of negative psychological conditioning. (23) The circadian rhythm is finely attuned to cues both from the environment and the brain. As patients experience sleep problems over time, they may begin to associate bed, bedtime, and the evening routine with difficulty falling asleep. Hyperarousal of the nervous system can result, making sleep more difficult and perpetuating symptoms of insomnia.
Sleep hygiene may be effective for mitigating temporary sleep difficulties associated with poor sleep habits or life circumstances. It also may complement more effective insomnia strategies such as Cognitive Behavioral Therapy for Insomnia, also known as CBT-I. CBT-I has extensive scientific support and a strong record of efficacy for chronic insomnia. (24)
The CBT-I protocol includes:
- Stimulus control therapy (SCT), which is designed to strengthen the association between the sleeping environment and sleep. SCT requires using the bed for sleep and sex only, getting out of bed if unable to sleep after ten minutes, returning to bed only when sleepy, going to bed and getting up at the same time every day, and foregoing naps
- Sleep restriction therapy. Sleep restriction limits time in bed to the average number of hours spent sleeping. The purpose of sleep restriction is to diminish the association between the sleeping environment and wakefulness. This therapy can help regulate the circadian rhythm and support improved sleep patterns. Sleep restriction is backed by extensive scientific studies, and can have a significant effect on insomnia symptoms. Sleep restriction increases the amount of time spent in deep, slow-wave sleep, and reduces the time spent waiting to fall asleep, also known as sleep latency.
- Cognitive therapy to address beliefs and anxieties about sleep. Education about sleep and the impact of erroneous beliefs has been proven to be an effective complement to other CBT-I therapies. Cognitive therapy can help establish new thought patterns, reduce anxiety, and dispel negative associations with sleep.
- Relaxation therapy. This protocol targets the hyperactivated nervous system that contributes to and perpetuates insomnia. Relaxation therapy is intended to interrupt negative thought processes as well as physical and nervous system tension. Relaxation techniques include progressive muscle relaxation, guided imagery, biofeedback, and breath training.
Last Word From Sleepopolis
The research in support of sleep hygiene as a treatment for more than temporary sleeplessness is limited and inconclusive. By contrast, Cognitive Behavioral Therapy for Insomnia is well-studied and proven effective for the majority of chronic insomnia sufferers.
Insomnia symptoms are common and typically transitory. Chronic insomnia lasting six months or longer is nearly always a result of negative psychological associations with the bed and the attempt to sleep, and is rarely the result of sleep hygiene or easy-to-correct lifestyle choices.
Sleep hygiene may be particularly helpful for those with poor sleep habits. Many sleep hygiene recommendations are effective for improving the sleep of people who are able to sleep well under normal circumstances, and when practicing common-sense behaviors such as caffeine avoidance. Most of us will experience temporary sleep difficulty at some point in life, and may benefit from improved sleep hygiene.
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- Sharon Schutte-Rodin, M.D., Clinical Guideline for the Evaluation and Management of Chronic Insomnia in Adults, Journal of Clinical Sleep Medicine, 2008
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- Natalie D. Dautovich, Variety is the Spice of Life: A Microlongitudinal Study Examining Age Differences in Intraindividual Variability in Daily Activities in Relation to Sleep Outcomes, The Journals of Gerontology, July 2015
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- Anne-Marie Chang, Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness, PNAS, Nov. 26, 2014
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