Insomnia, Sleep Disorders

Sleep disorders (Dyssomnias)

Sleep is a state of physical and mental rest when you become relatively inactive and unaware of your environment. Sleep plays a significant role in brain development, it is essential in maintaining normal levels of cognitive skills such as speech, memory, and thinking. And the lack of sleep has serious effects on the brain's ability to function properly.

Somnipathy is a term that refers to any disorder that involves sleep. Some examples of sleep disorders are:

  • Delayed sleep phase syndrome - the person cannot fall asleep or wake up at normally accepted times.
  • Hypopnea syndrome - too shallow or slow breathing during sleep.
  • Narcolepsy - a chronic sleep disorder where the brain is unable to regulate the body's sleep-wake cycles.
  • Obstructive sleep apnea - the person stops breathing for 10 or more seconds during sleep.
  • Periodic limb movement disorder - sudden jerks of an arm or leg during sleep.
  • Insomnia - when it is hard to fall asleep or stay asleep.
  • Rapid eye movement behavior disorder - abnormal behavior during REM (rapid eye movement) phase. The body starts to undergo complex integrated movements - as if the patient were physically acting out the dream.
  • Restless legs syndrome - a disorder which causes a strong urge to move your legs.
  • Somnambulism - sleepwalking.
  • Somniphobia (hypnophobia) - an abnormal fear of sleep.

Sleep cycle

As shown by electroencephalographic studies, the normal cycle of sleep consists of two distinct states:

  • REM (rapid eye movement) sleep, also called dream sleep, D state sleep, paradoxic sleep. Most dreams occur during REM sleep.
  • NREM (non-rapid eye movement or non-REM) sleep, also called S stage sleep.

Non-REM is divided into four stages[3]. The drowsy period is called Stage I sleep. Stage II sleep together with intermittent high-frequency spike clusters is called sleep spindles. Stage III sleep represents moderate to deep sleep. Stage IV -- slow-wave sleep -- is the deepest level of sleep. It is most difficult to awaken people during slow-wave sleep. The entire sequence from drowsiness to deep stage IV sleep usually takes about an hour.

Sleep begins with a stage I (sleep drowsiness) of NREM and deepens to NREM Stages II, III, and IV. The first REM period occurs about 80-120 minutes after onset of sleep and lasts about 10 minutes. After the first sleep cycle, NREM and REM sleep continue alternating cyclically. The duration of each cycle is approximately 90 minutes. Stages III and IV of NREM sleep (also known as deep sleep, delta sleep, or slow wave sleep) usually occur in the first two cycles. Later REM periods are longer (15–40 minutes), and the longest REM periods occur in the last third of the night.

What is insomnia?

Insomnia is a very common sleep disorder that affects most people at one time or another. Insomnia is more common among women and older adults but can occur in people of all ages and all social classes. Over the age of 65, 29% of men and 37% of women are affected.

Insomnia is an experience of inadequate or poor quality sleep characterized by one or more of the following problems: difficulty falling asleep (sleep onset insomnia), difficulty maintaining sleep, waking up too early in the morning, and non restorative sleep. It also involves daytime consequences such as fatigue, lack of energy, difficulty concentrating and irritability. Insomnia is not a serious medical condition but it can greatly affect the patient's work and social life.

Periods of sleep difficulty lasting between one night and a few weeks are referred to as acute (transient) insomnia. Chronic insomnia refers to sleep difficulty occurring at least three nights per week for one month or more. Over 90 percent of people experience transient or short-term insomnia at some point during their lives, and up to 30 percent of the general U.S. population struggle with chronic insomnia.

Sleep duration

Insomnia is not synonymous with short sleep.

Both short (less than 6 hours) and long (more than 8 hours) sleep duration are associated with increased mortality[1]. Several clinical studies[2] have found the best survival rates among people who sleep 7 hours per night.

Insomnia causes

There are many possible causes of insomnia. Sometimes there is one main cause, but often several factors interacting together will cause a sleep disturbance. Some conditions and situations that commonly lead to insomnia include:

  • Psychological Causes
    • Anxiety, a condition in which individuals feel increased tension, apprehension, and feelings of helplessness, fear, worry, and uncertainty. Everyday anxieties as well as severe anxiety disorders may keep your mind too alert to fall asleep.
    • Stress. Exposure to stress may contribute to the development or worsening of insomnia. Relationship problems, a chronically ill child, or an unrewarding career may contribute to sleep problems. If you suffer from these types of stresses, you should seek counseling to gain a new outlook on your troubles and more control in your life. Concerns about work, school, health or family can keep your mind too active, making you unable to relax.
    • Depression, a mood disturbance characterized by feelings of sadness, despair, and discouragement. About 90% of people with depression have insomnia. This may be due to chemical imbalances in the brain or because worries that accompany depression may keep person from relaxing enough to fall asleep.
    • Learned insomnia (also known as psychophysiological insomnia). Occurs when an individual worries so much about whether or not he/she will be able to go to sleep, that the person's bedtime rituals and behavior actually trigger insomnia. The more the person worries about falling asleep, the harder it becomes. Some individuals with learned insomnia have trouble sleeping in their own beds yet may fall asleep quickly when they don't intend to - while reading the newspaper, sleeping away from home, or watching TV. Just a few nights of poor sleep during a month can be enough to produce a cycle of poor sleep and increase the worry about it. Treatment for learned insomnia aims to improve sleep habits and reduce unnecessary worry.
  • Hormonal changes in women. These include premenstrual syndrome, menstruation, pregnancy, and menopause.
    • Menopause. Insomnia is frequently reported by women experiencing menopause. Insomnia can be a major problem in the first phases of menopause, when hormones are fluctuating intensely. Insomnia during this period may be due to different factors that occur. In some women, hot flashes, sweating, and a sense of anxiety can awaken women suddenly and frequently at night.
    • Menstruation. Progesterone promotes sleep, and levels of this hormone plunge during menstruation, causing insomnia.
    • Pregnancy. The effects of changes in progesterone levels in the first and last trimester can disrupt normal sleep patterns.
  • Decreased melatonin. The levels of melatonin, the hormone that helps control sleep, decrease as a person ages. By age 60, the body produces very little melatonin.
  • Medical conditions. These include allergies, arthritis, asthma, headache disorders, heart disease, gastroesophageal reflux, high blood pressure, restless legs syndrome, hyperthyroidism, Parkinson's disease. Such medical problems usually require the attention of a physician who can diagnose and treat the underlying condition. Treatment of the underlying cause of insomnia hopefully will result in improved sleep.
  • Pain. Pain and discomfort from a medical illness or injury often interfere with sleep.
  • Sleep related disorders. These include sleep apnea (in which one temporarily stops breathing during sleep) and periodic leg and arm movements during sleep (in which one's muscles excessively twitch or jerk). Severely disrupted breathing during sleep, known as sleep apnea, may affect people who breathe normally while they are awake. Breathing related sleep problems are most common in men, snorers, overweight people, and older adults.
  • Genetics. Problems with insomnia do seem to run in some families, although researchers have yet to identify how genetics play a role.
  • Jet lag. Air travel across time zones often causes brief bouts of insomnia. After long plane trips, one day of adjustment is usually needed for each time zone crossed. Traveling west to earlier times seems to be less traumatic than going east to a later time because it is easier to lengthen a circadian phase than to shorten it.
  • Working the night shift or long shifts. Individuals who work at night and those who work long shifts may have trouble adjusting their sleep habits. If you maintain later hours on weekends than during the week, you are more likely to experience sleep problems.
  • Medications. Insomnia can be caused by various medications, such as antidepressants, corticosteroids, high blood pressure medications. Many over-the-counter medications, including some pain medication combinations, decongestants and weight loss products, contain caffeine and other stimulants. Antihistamines may initially make you groggy, but they can worsen urinary problems, causing you to get up more during the night.
  • Long-term use of sleep medications. Sleeping pills often become less effective over time. If a person suddenly stops taking or becomes tolerant of a long term medication, insomnia may result. If you need sleep medications for longer than a few weeks, take them no more than two to four times a week, so they don't become habit forming.
  • Substance abuse:
    • Caffeine. Caffeine (contained in popular drinks like coffee, tea and cola or chocolate) is a stimulant and may prevent you from getting the sleep you need. The National Sleep Foundation reports the effects of caffeine can cause problems falling asleep as much as 10-12 hours later in some people. Consider halting your caffeine intake earlier in the day to ensure you get quality sleep.
    • Nicotine also stimulates the brain. Regular smokers often sleep very lightly and have reduced amounts of REM (rapid eye movement) sleep. They also tend to wake up after 3 or 4 hours of sleep due to nicotine withdrawal.
    • Alcohol. You may think that having a glass of wine will help you sleep. However, while it may help you fall asleep quickly, alcohol consumption is likely to produce interrupted sleep. After we have had a few drinks, alcohol often causes drowsiness and lets us get off to sleep quite easily. Later in the night, however, when the alcohol level in our blood decreases, our body's arousal mechanism is stimulated and our normal sleep pattern is impaired. In addition, one of the effects of alcohol is to stimulate the pouring of adrenalin into the bloodstream, causing arousal, sweating and palpitations. This can result in waking up half-way through the night, or earlier than normal, with the heart pounding, making it quite difficult to get to sleep again.
  • Inactive behavior. People whose lifestyles are very quiet or restricted may experience difficulty sleeping at night.
  • Excessive computer work.
  • Environmental factors. In one study, 20% of adults reported that light, noise, and uncomfortable temperatures caused their sleeplessness.
    • Noise. Traffic, airplanes, television, and other noises can disturb your sleep even when they don't cause you to wake up.
    • Light. It is well known that a person's biologic circadian clock is triggered by sunlight and very bright artificial light maintains wakefulness. Light affects your brain's production of the hormones that regulate sleep rhythms. Too much light in the bedroom can keep our body from deep sleep. Insufficient exposure to light during the day, as occurs in some disabled elderly patients who rarely venture outside, may also be linked with sleep disturbances.
    • Room temperature. Extreme temperatures and changes in the surrounding environment can contribute to sleepless nights. You will be restless if you are too hot or cold. A comfortable room temperature is best.
    • Sleep partner or other family members. A sleep partner who snores, has sleep apnea, is very restless, gets up frequently, or has difficulty sleeping will affect your ability to sleep. Interruptions from other family members, such as a toddler or new baby, can also keep you up.

Insomnia risk factors

The following factors may increase an individual's risk for insomnia:

  • Age. More than 50% of elderly people have insomnia[4]. Medical conditions that cause pain or nighttime distress are common in the elderly. Neurologic diseases in the elderly, such as Parkinson's, Alzheimer's, and other forms of dementia, can cause nighttime disorientation, confused wandering, and delirium. Older people are also prone to grief, worry, and anxiety, the handmaidens of sleeplessness. Older people are more sensitive to environmental disruptions, such as light, noise, or jet lag. Subtle and dramatic hormonal shifts also occur, including reductions in melatonin and growth hormone and increases in stress hormones, creating an imbalance that may reduce all stages of sleep.
  • Psychiatric problems. The strongest risk factors for insomnia are psychiatric problems and physical complaints, such as headaches and chronic pain, that have no identifiable cause (called somatic symptoms). About 90% of people with depression have insomnia. In addition, these conditions often coincide with somatic symptoms, particularly chronic pain. In fact, insomnia worsens chronic pain even in people who are not depressed. Headaches that occur during the night or early in the morning may actually be caused by sleep disorders.
  • Negative thinking. Negative thoughts and attitudes toward events can be significant factors in insomnia, however they do not cause insomnia in everyone.
  • Gender. Insomnia is more common in women than men. In women, a number of hormonal events can disturb sleep, including premenstrual syndrome, menstruation, pregnancy, and menopause. After childbirth, most women develop a high sensitivity to the sounds of their children, which causes them to wake easily. It is possible that many women never unlearn this sensitivity and continue to wake easily long after the children have grown. Older women who are not bothered by sleeplessness tend to have longer and better sleep than noninsomniac men their own age.
  • Working during night. Shift workers are at considerable risk for insomnia. Workers over 50 and those whose shifts are always changing are particularly susceptible, although night-shift workers also have a high rate of sleeplessness.
  • Childhood fears. One study found that people who had experienced long-term insomnia had been prone to nightmares and fear of the dark as children.


  • 1. Ikehara S, Iso H, Date C, Kikuchi S, Watanabe Y, Wada Y, Inaba Y, Tamakoshi A; JACC Study Group. Association of sleep duration with mortality from cardiovascular disease and other causes for Japanese men and women: the JACC study. Sleep. 2009 Mar;32(3):295-301. PubMed
  • 2. Kripke DF, Garfinkel L, Wingard DL, Klauber MR, Marler MR. Mortality associated with sleep duration and insomnia. Arch Gen Psychiatry. 2002 Feb;59(2):131-6. PubMed
  • 3. Purves D, Augustine GJ, Fitzpatrick D, et al.,Neuroscience. Stages of Sleep. 2nd edition. Sunderland: Sinauer Associates; 2001.
  • 4. Kamel NS, Gammack JK. Insomnia in the elderly: cause, approach, and treatment. Am J Med. 2006 Jun;119(6):463-9.

Created: August 18, 2006
Last updated: February 24, 2016

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