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What Are Sleep Disorders?

Sleep disorders involve problems with the quality, timing and amount of sleep, which cause problems with functioning and distress during the daytime. There are a number of different types of sleep disorders, of which insomnia is the most common. Other sleep disorders are narcolepsy, obstructive sleep apnea and restless leg syndrome.

Sleep Problems

  • Quality of sleep
  • Timing of sleep
  • Amount of sleep

Sleep difficulties are linked to both physical and emotional problems. Sleep problems can both contribute to or exacerbate mental health conditions and be a symptom of other mental health conditions.

In primary care, 10-20 percent of people complain of significant sleep problems. About one-third of adults report insomnia symptoms and 6-10 percent meet the criteria for insomnia disorder.1

  • Importance of Sleep

    Importance of Sleep

    Sleep is a basic human need and is critical to both physical and mental health. There are two types of sleep that generally occur in a pattern of three-to-five cycles per night:

    • Rapid eye movement (REM) – when most dreaming occurs
    • Non-REM – has three phases, including the deepest sleep

    When you sleep is also important. Your body typically works on a 24-hour cycle (circadian rhythm) that helps you know when to sleep.

    How much sleep we need varies depending on age and varies from person to person. Most adults need about seven to nine hours of restful sleep each night, according to the National Sleep Foundation. The Foundation revised its sleep recommendations in 2015 based on a rigorous review of scientific literature.

    Many of us do not get enough sleep. Nearly 30 percent of adults get less than six hours of sleep each night and only about 30 percent of high school students get at least eight hours of sleep on an average school night.2 An estimated 35 percent of Americans report their sleep quality as “poor” or “only fair.”3

    More than 50 million Americans have chronic sleep disorders.2

    Sleep Recommendations
    Age Hours of Sleep
    Infant (4-11 months) 12-15 hours
    Toddler (1-2 years) 11-14 hours
    Preschooler (3-5 years) 10-13 hours
    School-age child (6-13 years) 9-11 hours
    Teen (14-17 years) 8-10 hours
    Young adult (18-25 years) 7-9 hours
    Adult (26-64 years) 7-9 hours
    Older adult (65+ years) 7-8 hours
    Source: National Sleep Foundation

    Consequences of Lack of Sleep and Coexisting Conditions

    Sleep helps your brain function properly. Not getting enough sleep or poor quality sleep has many potential consequences. The most obvious concerns are fatigue and decreased energy, irritability and problems focusing. The ability to make decisions and mood can also be affected. Sleep problems often coexist with symptoms of depression or anxiety. Sleep problems can exacerbate depression or anxiety, and depression or anxiety can lead to sleep problems.

    Lack of sleep and too much sleep are linked to many chronic health problems, such as heart disease and diabetes. Sleep disturbances can also be a warning sign for medical and neurological problems, such as congestive heart failure, osteoarthritis and Parkinson’s disease.

  • Insomnia Disorder
  • Obstructive Sleep Apnea

Related Conditions

Other sleep disorders include:

  • Hypersomnolence disorder involves excessive sleepiness even when getting enough sleep and difficulty waking up (may be confused, not fully awake, for a period of time)
  • Narcolepsy involves excessive daytime sleepiness (“sleep attacks”) combined with sudden muscle weakness several times a week
  • Breathing-related sleep disorders (in addition to sleep apnea)
    • Central sleep apnea
    • Sleep related hypoventilation
    • Circadian rhythm sleep-wake disorders
  • Parasomnias (abnormal events or experiences during sleep)
    • Non-rapid eye movement sleep arousal disorders
    • Nightmare disorder
    • Rapid eye movement sleep behavior disorder
    • Restless legs syndrome – (associated with aches and pains throughout the legs which is relieved by movement of the leg, such as walking or kicking)


  1. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders (DSM-5), Fifth edition. 2013.
  2. Centers for Disease Control and Prevention. Insufficient Sleep is a Public Health Problem. Accessed July 2017.
  3. National Sleep Foundation. Sleep Health Index. 2014.
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