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Insomnia is the feeling of inadequate or poor sleep because of one or more of the following: trouble falling asleep; trouble remaining asleep; awakening too early; or non-restorative sleep. For insomnia to be diagnosed, these symptoms must be present at least three nights per week and the sleep difficulty present for at least one month. All of these symptoms can lead to daytime drowsiness, poor concentration, irritability, and the inability to feel refreshed and rested upon awakening. Approximately 70 million Americans are thought to have a sleep or wakefulness disorder, according to the Centers for Disease Control and Prevention. In 2014, approximately 35 percent of adults reported getting insufficient sleep.

Insomnia is not defined by the hours of sleep a person gets or how long it takes to fall asleep. Individuals vary in their need for and satisfaction with sleep, but individuals with insomnia experience distress or impairment in functioning as a result of their poor sleep.

Insomnia can be classified as episodic, persistent, or recurrent. Insomnia lasting from one month to three months is episodic. If the symptoms last three months or longer, the insomnia is said to be persistent. Insomnia is considered to be recurrent if two or more episodes occur within the space of one year.

The onset of insomnia symptoms can occur at any age, but the first episode is more common during young adulthood. Less frequently, insomnia begins in childhood or ad­olescence. In women, new-onset insomnia may occur during menopause and persist even after other symptoms, such as hot flashes, have resolved. Insomnia may also have a late-life onset, which is often associated with the onset of other health-related conditions.

Insomnia can be situational, persistent, or recurrent. Situational or acute insomnia usu­ally lasts a few days or a few weeks and is often associated with life events or rapid changes in sleep schedules or environment. It usually resolves once the initial event subsides. For some individuals, perhaps those more vulnerable to sleep disturbances, in­somnia may persist long after the initial event, possibly because of conditioning factors and heightened arousal.

The factors that precipitate insomnia may differ from those that perpetuate it. For example, an individual who is bedridden with a painful injury and has difficulty sleeping may then develop negative associations with sleep. Conditioned arousal may then persist and lead to persistent insomnia. A similar course may develop in the context of acute psychological stress or a mental disorder. For instance, insomnia that occurs during an episode of major depressive disorder can become a focus of attention, with consequent negative conditioning, and persist even after resolution of the depressive episode. In some cases, insomnia may also onset without any identifi­able triggering factor.

The course of insomnia may also be episodic, with recurrent episodes of sleep difficul­ties associated with the occurrence of stressful events. Chronicity rates range from 45 percent to 75 percent for follow-ups of one to seven years. Even when the course of insomnia has become chronic, there is night-to-night variability in sleep patterns, with an occasional restful night's sleep interspersed with several nights of poor sleep. The characteristics of insomnia may also change over time. Many people with insomnia have a history of "light" or easily disturbed sleep prior to the onset of more persistent sleep problems.

Insomnia complaints are more prevalent among older adults. The type of symptom changes because of age, with difficulties initiating sleep being more common among young adults and problems maintaining sleep occurring more fre­quently among middle-aged and older individuals.

Difficulties initiating and maintaining sleep can also occur in children and adolescents, but there are more limited data on prevalence, risk factors, and comorbidity during these developmental phases. Sleep difficulties in childhood can result from con­ditioning factors (a child who does not learn to fall asleep or return to sleep without the presence of a parent, for example) or from the absence of consistent sleep schedules and bedtime routines. Insomnia in adolescence is often triggered or exacerbated by irregular sleep sched­ules. In both children and adolescents, psychological and medical fac­tors can contribute to insomnia.


The diagnostic criteria of insomnia include difficulty falling asleep, difficulty maintaining sleep, and early-morning awakening with an inability to fall back to sleep. Sleep disturbances such as these cause significant distress and impairment in a multitude of areas in functioning, including social, academic, behavioral, and work.

Per the DSM-5, the primary symptom of insomnia is a predominant complaint of dissatisfaction with sleep quantity or quality. In addition, this will be associated with one (or more) of the following symptoms:

  • Difficulty initiating sleep. (In children, this may manifest as difficulty initiating sleep without caregiver intervention.)
  • Difficulty maintaining sleep, characterized by frequent awakenings or problems re­turning to sleep after awakenings. (In children, this may manifest as difficulty return­ing to sleep without caregiver intervention.)
  • Early-morning awakening with the inability to return to sleep.

The sleep disturbance causes clinically significant distress or impairment in social, oc­cupational, educational, academic, behavioral, or other important areas of functioning.

In order to garner a diagnosis of insomnia, the following conditions must also occur:

  • Sleep difficulty occurs at least 3 nights per week.
  • Sleep difficulty is present for at least 3 months.
  • Sleep difficulty occurs despite adequate opportunity for sleep.
  • The insomnia is not better explained by and does not occur exclusively during the course of another sleep-wake disorder (narcolepsy, a breathing-related sleep dis­order, a circadian rhythm sleep-wake disorder, a parasomnia).
  • The insomnia is not attributable to the physiological effects of a substance (an illicit drug, a medication).
  • Co-existing mental disorders and medical conditions do not adequately explain the pre­dominant complaint of insomnia (however, comorbid disorders may be present).
What is the difference between primary and secondary insomnia?

Insomnia can be considered primary or secondary. In primary insomnia, the cause of the insomnia is not immediately obvious and can’t be attributed to a physical or mental health condition, such as depression. In secondary insomnia, symptoms of insomnia appear to arise as a result of another condition, such as chronic pain, cancer, or heartburn; however, the insomnia may persist even after the primary condition has been resolved. Secondary insomnia is generally considered more common than primary insomnia.

What is the difference between sleep-onset insomnia and sleep-maintenance insomnia?

In sleep-onset insomnia, the individual has trouble falling asleep. In sleep-maintenance insomnia, the individual has trouble staying asleep. It’s also possible to have mixed insomnia, in which the individual has trouble both falling asleep and staying asleep. Sleep-onset insomnia is more prevalent in younger adults, while sleep-maintenance insomnia is more prevalent in older adults.

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Certain conditions seem to make individuals more likely to experience insomnia. Examples of these conditions include:

  • Advanced age (insomnia occurs more frequently in older adults)
  • Occurs more frequently among females
  • Having a history of depression

There are a number of possible causes of insomnia:

  • Shift work
  • Jet lag or other sleep-wake disturbances
  • Depression
  • Anxiety
  • Excessive worry
  • Stress
  • Grief
  • Intense excitement
  • Poor sleep conditions, such as a bed or bedroom not conducive to sleep
  • Use of nicotine, caffeine, alcohol, or stimulants
  • Eating before bedtime
  • Medications or illicit drugs
  • Medication withdrawal
  • A new medication
  • A change in medication
  • Bright-light exposure
  • Excessive daytime sleep
  • Excessive stimulation at bedtime, physical or intellectual
  • Overactive thyroid
  • Conditions that impair breathing
  • Arthritis or other chronic illness
  • Heartburn or other gastrointestinal condition
  • Co-occurring disorders or medical illness
  • Stroke
  • Restless leg syndrome
  • Aging
  • Menopause

Episodic or situational insomnia generally occurs in people who are temporarily experiencing one or more of the following. These can often be resolved on their own.

  • Stress
  • Environmental disturbances, such as noise
  • Change in environment
  • Extreme temperatures
  • Jet lag or other sleep-wake disturbances
  • Medication side effects

The more complex chronic insomnia often results from factors, including underlying physical or mental disorders. Depression, for one, is a common cause of chronic insomnia. Other underlying causes include asthma, sleep apnea, narcolepsy, restless legs syndrome, arthritis, kidney disease, heart failure, Parkinson's disease, and hyperthyroidism. Chronic insomnia may also be due to behavior problems, including the abuse of caffeine, alcohol, other substances, stress, shift work, or other lifestyle behaviors.

Some behaviors can exacerbate insomnia, or they may cause the sleep difficulty in the first place:

  • Worrying about difficult sleep
  • Excessive caffeine
  • Alcohol intake before bedtime
  • Smoking cigarettes before bedtime
  • Excessive afternoon or evening naps
  • Sleep-wake disruptions
Who is most at risk for insomnia?

Anyone can suffer from insomnia, but some populations have been found to be at greater risk than others. Women are at greater risk than are men, for example, and older adults are more at risk than younger adults. There is also evidence that insomnia rates vary by race and ethnicity. People of color—and especially Black and Latino people—appear to have an elevated risk of sleep disorders, including insomnia. Though the reasons for this disparity aren’t fully understood, heightened stress, unequal access to medical care, and a greater likelihood of working night shifts or irregular schedules have been proposed as potential causes.


Situational or episodic insomnia—from jet lag, for example—normally does not require treatment as episodes last only a few days or weeks. In these instances, the individual’s sleep cycle usually returns to normal without treatment.

In other cases of episodic insomnia, daytime sleepiness and impaired performance can be remedied with short-acting sleeping pills. However, extended use of these medications is not advised. They also come with side effects such as daytime haziness and impaired function. Over-the-counter medication is usually not recommended for insomnia. These non-prescription sleep aids contain antihistamines, which also can cause side effects of daytime sleepiness, dizziness, and confusion, among others.

There are behavioral techniques that can alleviate insomnia, including relaxation therapy, sleep restriction, reconditioning, and psychotherapy.

Relaxation Therapy: This technique can reduce or relieve anxiety and body tension. Relaxation through breathing exercises or biofeedback can help the individual's racing mind; relaxing the muscles may lead to restful sleep. However, it may take practice.

Sleep Restriction: Decreasing the time one spends in bed as well as avoiding daytime naps are helpful strategies. Doing so may increase the feeling of being tired, therefore increasing the hours one actually sleeps when in bed. A sleep restriction program allows only a few hours of sleep at night, gradually increasing the time until normal sleep returns.

Reconditioning or Stimulus Control: Reconditioning the individual into associating the bed with sleep can be a useful technique. In this case, the bed is used for sleep and sex and no other activities. The recommendations for this include:

  • Go to bed only when sleepy
  • If the individual is unable to sleep, he or she should get up
  • Stay up until sleepy
  • Avoid napping
  • Stick to a schedule; wake up and go to bed at the same time daily

Light Therapy: Using light therapy, with a light box, to help reset the internal clock is also a useful technique.

Cognitive Behavioral Therapy for Insomnia: Talking to a therapist or attending group therapy sessions can help reduce sleep anxiety. CBT-I, a form of CBT developed specifically to treat insomnia, focuses on thoughts and behaviors that disrupt sleep and teaches ways to promote good sleep hygiene.

CBT-I also reframes negative thoughts to positive ones and aims to help reconnect the concepts of "bed" and "sleep." Often, people who suffer from poor sleep link negative thoughts and anxious feelings with sleep; in many cases, they become anxious at the very thought of sleep, due to the persistent fear that they're not getting enough or won't be able to fall asleep. CBT-I aims to address these anxieties and teach strategies to calm a racing mind.

The individual may need to see the therapist weekly over two to three months. CBT-I can be delivered effectively either in person or online. For chronic insomnia sufferers, this therapy may be used alongside prescription medication. For people who suffer from both insomnia and major depressive disorder, a combination of antidepressant medication and CBT often proves effective.

For more on overcoming insomnia, visit our Sleep Center.

What are basic ways to get a good night's sleep?

In addition to good sleep hygiene, such as keeping one's bedroom conducive to sleep, it is helpful to set a schedule; get regular exercise of 20 to 30 minutes daily; avoid nicotine, caffeine, alcohol or heavy meals in the hours before bedtime, and, if unable to sleep, get up and read or listen to music until sleepy.

Does insomnia always need treatment?

No. Many cases of acute insomnia resolve on their own. If insomnia persists longer than a few weeks, and basic sleep hygiene practices do not ameliorate it, it may be time to see a primary care doctor or seek a referral to a sleep specialist.

Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition
National Heart, Lung, and Blood Institute Information Center
National Institute of Neurological Disorders and Stroke
National Institutes of Health - National Library of Medicine
Last updated: 04/20/2022