Causes of Sleep Disturbance: Why Insomnia and Sleeping Problems Happen

Sleep disorders arise from a wide range of causes, spanning individual differences in the nervous system, lifestyle habits, physical illness, breathing problems, circadian rhythm disruption, movement disorders, and psychological strain. As the physiologist I. P. Pavlov demonstrated, the depth and duration of sleep depend heavily on a person's individual characteristics, which is why the same trigger can leave one person sleepless while another sleeps soundly.

Causes of sleep disorders: a general overview

The causes of sleep disorders fall into several broad categories recognized in modern sleep medicine: behavioral and lifestyle factors, medical and neurological illness, sleep-disordered breathing, circadian rhythm disturbances, sleep-related movement disorders, and psychological or emotional stress. The International Classification of Sleep Disorders (ICSD), maintained by the American Academy of Sleep Medicine and now in its ICSD-3R revision, groups these conditions to guide diagnosis and treatment. Insomnia — difficulty falling or staying asleep despite adequate opportunity — is the most common complaint and often overlaps with the other categories.

• chronic sleep deprivation,
• sleep disturbance due to illness,
• chronic diseases,
• a change of surroundings,
• emotional worry,
• the effect of stimuli,
• an improper eating schedule,
• negative emotions,
• alcohol,
• sleep disturbance in older people,
• night shifts,
• a distorted sleep rhythm.

Individual features of the nervous system

Individual differences in nervous activity partly determine how easily a person sleeps. Some people, marked by a so-called excitable type of nervous activity, sleep little and fall asleep with difficulty, and rarely nap during the day.

Others, who have an inhibitory type of nervous system, fall asleep easily, like to sleep longer, and enjoy daytime naps.

The excitable and inhibitory types of nervous activity

The excitable and inhibitory types of higher nervous activity describe opposite tendencies in how quickly the brain shifts between arousal and rest. An excitable nervous system keeps cortical activity high, delaying the spread of inhibition needed for sleep onset, whereas an inhibitory system allows inhibition to dominate quickly. These constitutional differences help explain why identical bedtime conditions produce sound sleep in one person and restless wakefulness in another, and why treatment must be tailored to the individual rather than applied uniformly.

Chronic sleep deprivation

Chronic sleep deprivation makes a person naturally drowsy, and severe fatigue can create such a strong need for sleep (see: Sleep is essential for humans) that a person falls asleep in almost any conditions — at the wheel, on horseback, while walking. The Twardowski poem's hero Vasily Terkin captured this vividly, describing how he could sleep

"...on the march, in a boxcar, in a crush, in any hut, in a dugout or a cellar. Wherever chance may lead."

These cases are not insomnia but rather a sleep disturbance tied to unsettled living and surroundings. Once minimal conditions for sleep are provided, the duration of a person's sleep returns to normal. Repeated shortfalls, however, build what sleep researchers call sleep debt — an accumulating deficit between the sleep a person needs and the sleep they get. Sleep debt dulls perception of how impaired one actually is, so heavily sleep-deprived people routinely underestimate their own drowsiness. The Centers for Disease Control and Prevention treats insufficient sleep as a public-health problem, and the National Highway Transportation Safety Administration links drowsy driving to thousands of crashes each year. Recovering from accumulated deprivation can take several nights of extended, consistent sleep rather than a single long lie-in.

Lifestyle and harmful habits

Lifestyle and habits are among the most common and most correctable causes of poor sleep, covering diet, alcohol, stimulants, irregular schedules, and the modern tendency to delay bedtime. Behavioral scientists have described one such pattern as revenge bedtime procrastination — deliberately staying up late to reclaim personal free time after a demanding day, sacrificing sleep for a sense of control over one's own hours. Because these factors are behavioral, they respond well to changed routines and better sleep hygiene without medication.

An improper eating schedule

An improper eating schedule can directly cause disturbed sleep. A heavy meal or large volume of fluid before bed produces uncomfortable sensations that break up the depth of sleep. Natural coffee, strong tea, cocoa, and chocolate should not be consumed before bed, because they stimulate the nervous system and lead to disturbed sleep. Going to bed without having emptied the bowel and bladder also worsens sleep, making it shallow, broken, and anxious. As a general dietary rule for sleep quality, food and stimulating drinks are best finished about two hours before bedtime.

The effect of alcohol on sleep

Alcohol is a persistent cause of sleep disturbance, even in small doses taken before bed such as vodka, wine, or beer — and it is especially harmful to adolescents and to people who have suffered brain injury or other nervous-system disease. Sleep is most often wrecked in those who abuse alcohol; many experience sensory illusions before falling asleep, hearing rustling and knocking sounds.

People dependent on alcohol frequently have fantastical, frightening dreams, talk and walk in their sleep, and generally sleep in a shallow, anxious way. Their sleep is often interrupted by involuntary limb movements, convulsive starts, and twitches, and they may feel dizzy in sleep or experience sensations of falling and of the body moving through space.

At the same time such patients must seek help from medical institutions immediately, because sleep does not always improve even after drinking stops.

Night shifts and a distorted sleep rhythm

People who work night shifts have to alter their pattern of sleep and wakefulness. The body most often adapts easily, and shifting the hours of sleep does not affect well-being or health as long as the duration of sleep remains the same and sufficient to restore the body's strength. After night work a person should sleep well during the day; skipping this obligatory daytime sleep can cause fatigue, and prolonged sleep loss can lead to the development of neuroses.

In people with a weak nervous system, night work can cause marked mental and physical fatigue. Timely measures — switching to daytime-only work — or the necessary treatment and preventive steps quickly relieve this mental and physical exhaustion.

People who work mainly at night can temporarily develop a distorted sleep rhythm: even after they stop working nights, an ingrained habit leaves them needing to sleep during the day. Yet if they push through the daytime drowsiness for a few days, the normal rhythm of sleep and wakefulness quickly returns. This is essentially a self-imposed circadian shift, and the same principle underlies structured light exposure and consistent scheduling used to reset the body clock.

Sleep disturbance due to illness

Illness is one of the leading causes of disturbed sleep, particularly diseases of the respiratory and cardiovascular systems, gastrointestinal disorders, disorders of various nerves (radiculitis, neuralgia), and tooth problems. In these cases the sleep disturbance is driven by painful conditions of the body that, through their severity or other factors, prevent the patient from falling asleep and make sleep broken and anxious.

In the evening hours, as the number of external stimuli falls, so does the number of so-called competing foci of excitation, which intensifies the pain sensations caused by the illness.

The "stagnant" focus of excitation, being a consequence of the body's diseased state, then becomes dominant, and insomnia sets in. Treatment of insomnia in these cases should follow the path of treating the underlying disease, since relieving the pain usually normalizes sleep. The return of sleep in such patients is often one of the first signs of approaching recovery. Chronic pain conditions such as fibromyalgia illustrate this link clearly, keeping sufferers in a light, fragmented sleep until the pain itself is controlled.

Chronic illnesses as a cause of insomnia

Certain chronic poisonings and diseases of the endocrine glands can also produce various sleep disturbances, and long-standing medical conditions frequently underlie stubborn insomnia. Large cohort studies such as the Wisconsin Sleep Cohort Study and the Multi-Ethnic Study of Atherosclerosis have documented how chronic disease and disrupted sleep reinforce one another over time.

Cardiovascular disease and hypertension

Cardiovascular disease and hypertension readily disturb sleep, and people suffering from high blood pressure and cerebral vascular sclerosis tend to sleep restlessly. They often wake from a feeling of fear or a jolt and then cannot fall asleep again for a long time. Poor sleep and heart disease act in both directions: untreated sleep-disordered breathing raises blood pressure, while cardiovascular illness fragments sleep, so managing one condition supports the other.

Diseases of the endocrine glands

Diseases of the endocrine glands — the thyroid, the adrenal glands, or the ovaries — are a recognized physical cause of sleep disturbance, because they alter the hormones that regulate arousal and rest. Thyroid overactivity speeds metabolism and drives a light, agitated sleep, while hormonal shifts during pregnancy commonly cause pregnancy-related insomnia. Metabolic conditions such as Type II Diabetes are likewise associated with poorer sleep, reflecting how closely the endocrine system and sleep regulation are intertwined.

Breathing disorders in sleep (apnea)

Sleep-disordered breathing is a major and often underdiagnosed cause of unrefreshing sleep, in which breathing repeatedly pauses or becomes shallow during the night. The two main forms are obstructive sleep apnea and central sleep apnea, distinguished by whether the airway is blocked or the brain fails to signal the breathing muscles. Both fragment sleep, lower blood oxygen, and leave the person exhausted by day despite spending a full night in bed.

Obstructive sleep apnea

Obstructive sleep apnea (OSA) occurs when the soft tissues at the back of the throat relax and collapse during sleep, blocking airflow until the sleeper briefly rouses to reopen the airway. Loud snoring, choking or gasping episodes, and heavy daytime sleepiness are the classic signs, and snoring is often the first clue that the airway is partly obstructing. The Wisconsin Sleep Cohort Study found the condition is common and frequently undiagnosed, and it is more prevalent in men and in people carrying excess weight. The standard treatment is continuous positive airway pressure — a CPAP machine that delivers a steady stream of air to hold the airway open through the night.

Central sleep apnea

Central sleep apnea differs from the obstructive form in that the airway stays open but the brain temporarily stops sending the signal to breathe. It is linked to heart failure, stroke, and neurological disease, and long-term opioid use is a well-recognized trigger because opioids suppress the brain's respiratory drive. Because the mechanism is neurological rather than mechanical, evaluation typically involves a full overnight sleep study, and management focuses on the underlying cause together with tailored breathing support.

Circadian rhythm disorders

Circadian rhythm sleep-wake disorders arise when a person's internal body clock falls out of step with the external day-night cycle, so that the drive to sleep comes at the wrong time. The circadian rhythm is governed by light, and disruption from shift work, irregular schedules, or travel across time zones leaves people unable to sleep when they want to and struggling to stay awake when they should. Melatonin, a hormone released by the body as darkness falls, and carefully timed light exposure are the main tools used to nudge the clock back into alignment.

Crossing time zones (jet lag)

Jet lag is a temporary circadian rhythm disorder that appears after rapid travel across several time zones, when the internal clock still runs on the departure time while the destination demands a different schedule. Symptoms include difficulty falling asleep, waking too early, daytime fatigue, and poor concentration until the body clock resets, usually by roughly a day per time zone crossed. Gradually shifting bedtime before travel, seeking bright light at the right hours, and short-term use of melatonin can shorten the adjustment.

Disruption of the daily sleep-wake rhythm

A disrupted daily sleep-wake rhythm develops when bedtime and wake time drift unpredictably rather than following a stable pattern, which is common among shift workers, adolescents, and anyone with an irregular routine. Sleep can move much later or much earlier than conventional hours, or scatter across the day, leaving the person out of sync with work, school, and social life. The most powerful correction is a consistent schedule anchored by fixed wake times and controlled light exposure, reinforcing the body's natural cues each day.

Movement disorders during sleep

Sleep-related movement disorders are conditions in which involuntary movements interfere with falling or staying asleep, and they are a distinct category of the ICSD. Beyond the leg movements described below, teeth grinding — bruxism — and periodic limb movements during sleep also fragment rest and often go unnoticed by the sleeper until a bed partner or a sleep study reveals them.

Restless legs syndrome

Restless legs syndrome (RLS) is a neurological condition marked by an uncomfortable, irresistible urge to move the legs, typically in the evening and at rest, which eases with movement but returns as soon as the person settles. Because the urge peaks at bedtime, RLS is a frequent cause of difficulty falling asleep, and it often coexists with periodic limb movements that jolt the sleeper throughout the night. It is associated with low iron stores, pregnancy, and some chronic conditions, and treatment addresses the underlying cause along with medication where needed.

Hypersomnia and narcolepsy

Hypersomnias are disorders of excessive daytime sleepiness in which a person sleeps enough at night yet remains overwhelmingly drowsy by day, and they form the central disorders of hypersomnolence in the ICSD. Narcolepsy is the best-known example: a chronic neurological disorder in which the brain cannot properly regulate the boundary between sleep and wakefulness, producing sudden sleep attacks and, in some people, cataplexy — an abrupt loss of muscle tone triggered by emotion. Narcolepsy has a genetic component and is diagnosed with an overnight sleep study followed by a multiple sleep latency test that measures how quickly a person falls asleep during the day. Wake-promoting medications such as modafinil are commonly used to manage the daytime sleepiness.

Psychological causes: worry and emotion

Psychological strain is one of the most powerful causes of insomnia, since worry, grief, and heightened emotion keep the mind aroused when the body is ready for rest. Under certain conditions, particularly in older age or after severe emotional experiences, a break in a person's usual routine can lead to serious disturbance. Mental-health conditions including anxiety, depression, and post-traumatic stress disorder are closely tied to chronic insomnia, each feeding the other.

A 51-year-old patient had never been seriously ill before but had always been somewhat anxious by nature. One autumn day she did not sleep the whole night. The insomnia had been preceded by a week during which, waiting for her husband who worked until late at night, she fell asleep only once he came home. From that point, for a whole year, she could sleep only with the help of sleeping pills. In September, when her son was admitted for surgery, her insomnia became even more stubborn. The medications stopped working. The patient developed thoughts about the hopelessness of treatment, a depressed mood, and even thoughts of death. But after prolonged combined treatment in hospital — medication together with physiotherapy, psychotherapy, and occupational therapy — her sleep normalized and she was discharged home in good condition.

Negative emotions and stress

Negative emotions such as anger, despair, hatred, and jealousy are among the important causes that reduce the depth and length of sleep. During a state of emotional arousal, the adrenal hormone adrenaline pours into the blood, exciting the subcortical brain cells and setting off a clash between the opposing processes of inhibition and excitation. The result is a so-called nervous breakdown that leads to insomnia.

People differ markedly in their sleep reactivity — how strongly a stressful event disturbs their sleep. Those with high reactivity respond to worry with racing thoughts and a pounding heart at bedtime, which is why the same setback can rob one person of a night's rest while barely touching another. Recognizing this tendency is the first step toward calming the pre-sleep mind rather than reaching for medication.

Change of surroundings and place of sleeping

A change of surroundings and of the place where a person sleeps can bring on sleep disturbance. It is well known that some people sleep poorly as guests, on a train, or during their first days in a sanatorium or rest home. As they adapt to the new conditions, their sleep quickly returns to normal. This is a common, self-limiting form of transient insomnia rather than a lasting disorder.

The effect of stimuli

Sleep is often disrupted by the sudden cessation of habitual stimuli acting on a person. For example:

• A train conductor sleeping peacefully in a rattling train wakes the moment the train stops.
• A person wakes when a clock stops ticking.

In these cases a "sentinel" point has formed in the brain, tuned to particular circumstances: for the conductor, the stopping of the train is the "signal" to organize the boarding and disembarking of passengers. This shows how the sleeping brain remains partly monitoring the environment, which is why an unfamiliar or over-stimulating bedroom can keep sleep light and easily broken.

Sleep disturbance in older people

Short sleep in older people is closely tied to changes in the blood vessels of the brain. Over the years these vessels undergo significant change: they become less elastic, stiffer, and narrower, and the delivery of nutrients and oxygen to brain cells through the altered vessels worsens.

For the same reason it becomes harder to clear the "waste products" that accumulate from constant metabolism. As a result the normal functioning of the processes of excitation and inhibition — so important for the alternation of wakefulness and sleep — is disturbed. Insomnia is genuinely more common with age, and older adults are also more likely to have chronic pain, cardiovascular disease, and neurological conditions such as Parkinson's disease and Alzheimer's dementia that further fragment sleep. Because several factors usually combine, sleep problems in older people are best assessed as a whole rather than treated with sedatives alone.

Sleep disturbance in children

Sleep problems in children are frequently caused by failure to keep a precise bedtime. Exciting games that stir a child's imagination, and unsettling stories or events in daily life, not only lead to late falling asleep but also make children's sleep broken and restless. Evening visits to the theater or cinema can likewise cause poor sleep.

In recent years one of the frequent causes of disturbed sleep in children has been watching late television programs and becoming absorbed in the computer. Screens naturally attract many children, who — out of curiosity and a lack of established routine — watch whatever appears and play whatever games they find.

Parents often not only fail to limit their children's screen time and choice of programs but even view such pastimes indulgently, seeing them as a way to keep children away from the harmful influence of the street and unreliable friends. Kind-hearted mothers say that television and the computer "save" their children from exhausting outdoor games, entirely forgetting the other side of the coin. Studies of large numbers of children who are constant viewers and heavy computer users have found in them signs of uneven overwork and disturbed sleep.

Teachers in the suburbs of Paris report that on Mondays children "nod off" in lessons, linking this to fatigue from long weekend viewing and time at the computer. Where this can lead is shown by the following example.

Seryozha, 9 years old, was unable to fall asleep for a very long time. He would just close his eyes, then jerk and start to cry. His mother's affection did not calm him. His worried parents searched in vain for the cause of his distress. Only his grandmother — an experienced doctor who watched Seryozha at night, observing his movements and facial expression and listening to the barely intelligible phrases he spoke in his sleep — suspected that he was in a state of nervous excitement caused by the programs he had watched for so long on television. Through skillful questioning the boy confirmed that in his sleep he saw many episodes from the television programs and that he seemed to go on living in the world of the frames he had seen on the screen.

Children are very impressionable and often react to what they see and hear vividly and intensely. Moreover, children's perception and thinking differ from an adult's in being predominantly image-based.

Children most often remember and "reason" not in words but in images, and this feature helps explain restless sleep in the young. Prolonged mental strain in the evening hours — solving difficult problems, a long game of chess — can also disturb a child's sleep.

How insomnia develops

Chance sleep disturbances and disorders are made worse, entrenched, and turned into genuine insomnia by the wrong attitude of certain anxious, suspicious people toward these accidental triggers of a broken sleep-onset process. As soon as such a person fails to fall asleep on time a few times, they stock up on various sleeping pills.

The easy availability of many sedative and hypnotic medicines in pharmacies encourages "self-treatment". Trusting their own "expertise" and the "magical" effect of patented remedies, such patients start taking them ever more often, "just in case", grow habituated, and — if they do not stop in time — become dependent. Continuing to poison body and brain, they only intensify the insomnia. Others become extremely anxious at the first sleep "failures", dreading the onset of night hours before bedtime and thinking obsessively about how they will surely not sleep again.

Once in bed they turn from side to side every minute, sighing, groaning, getting up and lying down again, with a single thought in mind — how to fall asleep, faster, faster. And sleep, like a frightened dove, flies farther away the more you chase it. This vicious cycle of trying too hard is exactly what modern cognitive behavioral therapy for insomnia sets out to break.

Daytime effects and complications of sleep disorders

The consequences of poor sleep reach far beyond the night, affecting mood, thinking, and physical health during the day. Insufficient or fragmented sleep impairs concentration, memory, and reaction time, raising the risk of errors and accidents, and drowsy driving is a documented cause of serious road crashes. Over the longer term, chronic sleep loss is associated with high blood pressure, cardiovascular disease, metabolic problems, weakened immunity, and worsened mental health, which is why sleep is treated as a pillar of overall health rather than an optional luxury.

Diagnosing the causes of a sleep disorder

Diagnosing a sleep disorder begins with a careful history of sleep habits, timing, and daytime symptoms, often supported by a sleep diary and by wearable devices such as an actigraph that track rest and activity over days or weeks. When a physical disorder is suspected, an overnight polysomnography study in a sleep laboratory records brain waves, breathing, oxygen levels, heart rhythm, and limb movements to detect sleep apnea, movement disorders, and other conditions. A home sleep study offers a more convenient option for suspected obstructive sleep apnea, while a multiple sleep latency test measures daytime sleepiness when narcolepsy is being evaluated. Identifying the underlying cause is essential, because insomnia driven by pain, apnea, a circadian problem, or anxiety each calls for a different treatment.

Methods of treating and normalizing sleep

Treatment of insomnia and sleep disturbance depends on the cause, and often a doctor's clear explanation of the true reason, together with timely advice, is enough. Physical and spa-based methods and remedies that lack a direct hypnotic effect play a large role, and effective management usually combines several approaches rather than relying on a single drug. In cases where routine measures must be paired with sleeping medicines, those medicines should be taken only as prescribed by a doctor and only in the doses ordered.

In recent years, alongside hypnotics, many agents with a calming and relaxing effect on the nervous and muscular systems have appeared. These are used successfully in treating various nervous and mental disturbances, including sleep disorders, but they too help only when taken strictly according to a doctor's instructions. Where medication is warranted, prescribing physicians may use short-term hypnotics such as zolpidem, and select drugs are reserved for specific conditions — for instance, wake-promoting agents for daytime sleepiness in narcolepsy. Methods that use the physiological mechanisms of conditioned-reflex sleep — hypnosis, suggestion, electrosleep, and electropharmacotherapy — have also been developed. It is very important to learn to give oneself over fully to a feeling of calm and rest, ideally linking that feeling to pleasant images such as landscapes or memories of the sea.

Cognitive behavioral therapy for insomnia

Cognitive behavioral therapy for insomnia (CBT-I) is the recommended first-line treatment for chronic insomnia and works by changing the thoughts and behaviors that keep sleep broken. Rather than sedating the patient, CBT-I retrains the sleep system through several components:

• stimulus control — reserving the bed for sleep so the brain re-associates it with rest rather than wakeful frustration;
• sleep restriction — temporarily limiting time in bed to consolidate fragmented sleep and rebuild sleep drive;
• cognitive restructuring — challenging the anxious "I'll never sleep" thinking that fuels the vicious cycle;
• relaxation training and consistent sleep-hygiene habits.

Because CBT-I addresses the causes rather than masking symptoms, its benefits tend to last longer than those of hypnotics and it avoids the risk of dependence that comes with long-term pill use.

Treating the underlying disease

Treating the underlying disease is the cornerstone of relief whenever insomnia is secondary to another condition. When sleep is broken by pain, endocrine disorder, cardiovascular disease, or sleep-disordered breathing, controlling that condition usually normalizes sleep — relieving pain, stabilizing blood pressure, or providing CPAP therapy for obstructive sleep apnea. This is why identifying the true cause matters so much: sedatives layered on top of an untreated illness suppress a symptom while leaving the driver of the insomnia in place.

The method of self-suggestion

The method of self-suggestion — relaxation, or autogenic training, developed in Germany — has recently spread as a way to bring on sleep without medication. In this method the patient learns to suggest to themselves the appropriate imagery of sleep, which then triggers its rapid onset.

That self-suggestion can be highly effective is something everyone knows from the example of a pre-planned awakening at a set time, which in most cases occurs punctually. In the same way, suggestions aimed at falling asleep can be realized. A person who wants to learn self-suggestion can master this fairly simple technique only with the help and under the guidance of a doctor, and the wording of the suggestions will differ according to the nature of the sleep disturbance and the individual features of the sufferer.

Measures to prevent sleep disturbances and sleep hygiene

Good sleep hygiene is the most reliable prevention against most sleep disturbances, building the conditions and habits that let full, natural sleep come easily. The following measures form a practical checklist:

• Develop the habit of going to bed and getting up at fixed hours. A set falling-asleep time, repeatedly combined with the same setting (darkness, quiet), itself brings on sleep.
• Finish eating and stimulating drinks (coffee, tea, cocoa) at least two hours before bed. Immediately before sleep you may have only a glass of soured milk or kefir. This is especially important for children.
• Remember that sweets, candy, and especially chocolate should be excluded from children's evening diet, as they contain substances that stimulate the nervous system and delay the onset of sleep. Spicy dishes with pepper and various seasonings have the same effect. Sleep cannot be replaced by anything — a point over-attentive mothers who believe children must be well fed before bed should keep in mind.
• Half an hour, and better still an hour before sleep, schoolchildren and adults engaged in mental work should stop their tasks. When something urgent arises, it is better to get up an hour earlier than to go to bed later than usual. "Chasing away" sleep by working past the usual bedtime is harmful, because after overcoming drowsiness a person becomes agitated and can then no longer fall asleep, or does so only with difficulty.
• Preschool children and schoolchildren should not be allowed to watch television after 9 p.m., and should watch only programs suited to their age; the same applies to films and computers. Physical exercise and games such as chess, draughts, and cards should be avoided before bed.
• A short walk in fresh air before bed is beneficial, as it calms the nervous system and promotes sound sleep.
• Children should sleep separately from their parents, each in their own bed.
• Air the room before sleep. Many people sleep badly in a stuffy room because unventilated air, besides dust, contains much carbon dioxide, which irritates the nerve endings of the airways and creates a focus of excitation in the cerebral cortex that hinders the spread of inhibition.
• Create the necessary hygienic conditions for sleep: a clean, comfortable bed, a soft pillow, and for some people a warm blanket. A duvet cover has real hygienic value, protecting the skin from direct contact with the blanket, which is often a source of irritation. The bed should be long and wide enough.
• Make sure mattresses stay springy and do not become lumpy; air, beat, and shake them out in the open as often as possible.
• Sleeping in nightclothes is recommended.
• A full or foot bath before bed is helpful — but not a shower, which stimulates rather than calms the nervous system.
• In bed, try to relax all the joints and muscles and take a comfortable position.
• Do not cover the head with the blanket or bury the face in the pillow, as this hinders breathing; the hands should stay above the blanket, which is especially important for children and adolescents.
• Do not linger in bed after waking. Get up at once, do some physical exercises, and take water treatments.
• Remember that active wakefulness and varied, invigorating work throughout the day promote good, sound sleep at night. For a healthy adult, therefore, an after-dinner nap is not only useless but harmful; only sick or weakened people and children benefit from sleeping after a meal.
• For older people, a short rest in bed or in an armchair after dinner can be recommended.

Long before modern sleep science, physicians warned against the daytime nap for adults. The following verse comes from the Salerno Code of Health, published in 1480 in the Italian town of Salerno:

"Let midday sleep be brief, or let there be none at all. Headache and catarrh, fever and heavy weakness — all these you will surely earn yourself through a midday sleep."

The lines show that doctors noticed the negative influence of daytime sleep on adults centuries ago: a nap makes the night's sleep shorter and slower to arrive, which is why a consistent single sleep period at night remains the healthiest pattern for most adults.