Insomnia Disorder

Core concept

Predominant dissatisfaction with sleep quantity or quality, with difficulty initiating sleep, difficulty maintaining sleep, or early-morning awakening with inability to return to sleep, occurring at least 3 nights per week for at least 3 months, causing clinically significant distress or impairment, despite adequate opportunity for sleep.

Plain-language explanation

Insomnia Disorder is diagnosed when a person's sleep difficulty -- trouble falling asleep, staying asleep, or waking too early -- happens often enough (3+ nights a week), for long enough (3+ months), and is disruptive enough to daytime functioning that it rises above an occasional bad night. It also requires that the person actually had adequate opportunity to sleep -- if someone simply isn't giving themselves enough time in bed, that's not insomnia.

Developmental considerations

Can occur at any age; often begins with an identifiable precipitant (stress, illness, schedule change) but becomes a distinct, persistent disorder when perpetuated by learned associations and behaviors (e.g., anxiety about sleep itself, compensatory behaviors) well after the original trigger resolves.

Functional impact

Associated with impaired concentration, mood disturbance, fatigue, reduced work/school performance, and increased risk of accidents; chronic insomnia is also linked to elevated risk for developing or worsening co-occurring depressive and anxiety disorders.

Associated features

Hyperarousal (both cognitive and physiological) around bedtime is common; conditioned/learned negative associations with the bed or bedtime routine often develop and perpetuate the disorder independent of the original trigger.

Cultural considerations

Expected sleep schedules, napping norms, and co-sleeping arrangements vary across cultures and can affect both the experience and reporting of sleep difficulty; clinicians should assess against the person's own typical patterns and expectations rather than a single universal sleep norm.

Common misconception

A common misconception is that Insomnia Disorder is simply a symptom of depression or anxiety and doesn't need to be addressed as its own diagnosis or treatment target. DSM-5-TR treats it as a distinct disorder that can co-occur with (rather than always being secondary to) mood and anxiety disorders, and it often requires and responds to its own targeted treatment (e.g., CBT-I) even when a co-occurring disorder is also treated.

Reconsider this formulation

If the sleep difficulty occurs fewer than 3 nights per week, has lasted less than 3 months, or is fully explained by inadequate sleep opportunity rather than an inability to sleep, reconsider that criteria are not met. If it occurs only during a well-defined mood or anxiety episode and resolves with it, evaluate whether it should be treated as a feature of that condition rather than a separate co-occurring diagnosis.

Example fictional case

For the past five months, a person has struggled to fall asleep most nights, lying awake for over an hour despite going to bed with adequate opportunity to sleep, and reports significant daytime fatigue, irritability, and difficulty concentrating at work as a result -- a pattern that began after a stressful life event but has persisted well beyond it.

References

APA (2022). DSM-5-TR, Sleep-Wake Disorders.

Recognition pattern

Dissatisfaction with sleep quantity/quality via difficulty initiating sleep, difficulty maintaining sleep, or early-morning awakening, 3+ nights/week for 3+ months, despite adequate sleep opportunity, causing clinically significant distress or impairment in daytime functioning, and not better explained by another sleep-wake disorder, substance, or co-occurring condition alone.

What to notice

• Difficulty initiating sleep, maintaining sleep, or early-morning awakening with inability to return to sleep
• Occurs 3+ nights per week for 3+ months
• Despite adequate opportunity for sleep
• Causes clinically significant distress or daytime impairment

Distinguish

Distinguish from insomnia that is fully accounted for by another sleep-wake disorder, an inadequate sleep opportunity, or an exclusively episode-limited feature of a mood or anxiety disorder.

Differential considerations

Insomnia that occurs exclusively during the course of another sleep-wake disorder (e.g., a breathing-related sleep disorder) is not diagnosed separately unless it's independently the focus of clinical attention and severe enough to warrant its own treatment. Short sleep duration alone, without dissatisfaction or impairment, is not insomnia -- some people are naturally short sleepers.

Commonly confused conditions

• Generalized Anxiety Disorder
• Major Depressive Disorder

Related comparisons

Reasoning prompts

• Was there actually adequate opportunity to sleep, or is short sleep explained by insufficient time in bed?
• Does the sleep difficulty meet the frequency (3+/week) and duration (3+ months) thresholds, or is this a shorter-term, situational disturbance?

Clarifying questions to ask

• Does sleep quality normalize when the person is allowed to sleep on their own preferred schedule?
• Is there a specific schedule conflict (shift work, school start time, travel) driving the complaint?
• What do sleep diaries or actigraphy show across an unconstrained period?
• Is the person's worry primarily about sleep itself, or does it span many life domains with sleep as just one part of it?
• Does the sleep difficulty independently meet the 3-nights-a-week, 3-month threshold regardless of the anxiety picture?
• Would treating the worry alone likely resolve the sleep difficulty, or does the sleep problem need its own independent treatment target?
• What specific criterion of Insomnia Disorder is not met here?
• Has Insomnia Disorder been actively ruled out, rather than simply not yet confirmed?
• Is there a specific substance or medication with known sleep effects, and does the severity exceed what's typically expected from it?
• Does the sleep disturbance persist on its own timeline (3+ nights weekly, 3+ months) independent of the substance?

Case Lab

Practice questions

2 question(s) reference this disorder. Practice Insomnia Disorder →