What is Insomnia?
Insomnia is difficulty falling asleep, staying asleep, or waking too early despite adequate opportunity to sleep, with daytime consequences such as fatigue, poor concentration, or low mood. Chronic insomnia means this occurs at least three nights a week for three months or longer. Cognitive behavioural therapy for insomnia (CBT-I) is the recommended first-line treatment.
Key takeaways
- Insomnia is defined by daytime impact as well as nighttime difficulty — sleeping less than average is not itself a disorder.
- Chronic insomnia means at least three nights a week for at least three months.
- CBT-I is the first-line treatment and outperforms sleep medication over the long term.
- Sleeping pills have a role but are generally intended for short-term or intermittent use.
- Insomnia frequently coexists with depression, anxiety, pain, and sleep apnea, and treating it improves those too.
Overview
Insomnia is the most common sleep complaint, affecting roughly a third of adults at some point and persisting as a chronic disorder in around one in ten. It has three presentations that often overlap: difficulty falling asleep, difficulty staying asleep with prolonged awakenings, and waking far earlier than intended. The essential feature is that the difficulty occurs despite having the time and the environment to sleep — someone who sleeps six hours because of a demanding schedule has insufficient sleep, not insomnia.
What turns a few bad nights into a chronic problem is usually the response to them. Spending longer in bed to catch up, napping, checking the clock, and worrying about the consequences of poor sleep all weaken the association between bed and sleep and increase arousal at exactly the wrong time. This is the mechanism that cognitive behavioural therapy for insomnia targets, and it is why the recommended first-line treatment is behavioural rather than pharmacological.
What Insomnia is
Chronic insomnia disorder is diagnosed when sleep difficulty occurs at least three nights per week for at least three months, with associated daytime impairment, despite adequate opportunity for sleep. Short-term insomnia disorder describes the same picture lasting less than three months, often clearly linked to a stressor.
A useful model describes predisposing traits (a tendency toward hyperarousal or worry), a precipitating event (illness, bereavement, job stress, a new baby), and perpetuating factors (extended time in bed, napping, clock-watching, caffeine, and anxiety about sleep). The precipitating event often resolves while the perpetuating factors keep the insomnia going — which is why treatment targets those.
Common symptoms
Insomnia has nighttime features and daytime consequences, and both are needed for the diagnosis.
- Difficulty falling asleep at the start of the night
- Waking during the night and struggling to fall back asleep
- Waking earlier than intended and being unable to return to sleep
- Daytime fatigue, low energy, or feeling unrefreshed
- Difficulty concentrating, remembering, or paying attention
- Irritability, low mood, or increased anxiety
- Worry or frustration about sleep, often building through the evening
Less common symptoms
- Increased errors or near-misses at work or when driving
- Physical tension, headaches, or gastrointestinal upset
- Reduced motivation or reluctance to make social plans
- A sense of sleeping far less than a sleep tracker or partner reports (paradoxical insomnia)
Risk factors
- Female sex — insomnia is roughly 1.5 times more common in women, with peaks around pregnancy and menopause
- Older age — sleep becomes lighter and more fragmented, and medical contributors accumulate
- Anxiety, depression, and high stress — bidirectional and among the strongest associations
- Chronic pain conditions — pain fragments sleep and poor sleep amplifies pain
- Shift work and irregular schedules — misalign the internal clock with the sleep opportunity
- Caffeine, nicotine, and alcohol — alcohol shortens sleep onset but fragments the second half of the night
- Untreated sleep apnea, restless legs syndrome, or nocturia — cause awakenings that get labelled as insomnia
- Certain medications including some antidepressants, stimulants, steroids, and decongestants
Causes
Insomnia is best understood as a state of hyperarousal that persists into the night — physiological, cognitive, and emotional. People with chronic insomnia show higher measures of arousal around the clock, not only at bedtime, which is why simply feeling tired does not translate into falling asleep. Genetics contribute to this tendency, and stressful life events commonly trigger the first episode.
Behavioural and cognitive responses then sustain it. Extending time in bed reduces the biological drive for sleep and dilutes it across more hours; the bed becomes associated with wakefulness and frustration; and anxious monitoring of sleep raises arousal further. Underlying medical and psychiatric conditions, medications, and other sleep disorders should always be considered, since treating them changes the picture substantially.
How it is diagnosed
Insomnia is diagnosed clinically from the history; sleep studies are used only when another sleep disorder is suspected.
| Test or assessment | What it looks at |
|---|---|
| Clinical sleep history | Covers timing, duration, sleep environment, daytime impact, substance use, and medication. This is the core of the diagnosis. |
| Sleep diary | A one-to-two-week record of bedtimes, wake times, awakenings, and daytime function. It is more informative than recall and forms the basis of CBT-I. |
| Validated questionnaires | Tools such as the Insomnia Severity Index quantify severity and track change over time. |
| Screening for other sleep disorders | Questions about snoring, witnessed apneas, leg discomfort at rest, and unusual nighttime behaviours help identify sleep apnea, restless legs, or parasomnias. |
| Targeted blood tests | Thyroid function, ferritin (relevant to restless legs), and other tests as guided by the history rather than routinely. |
| Polysomnography | An overnight sleep study, not needed for uncomplicated insomnia. It is used when sleep apnea, periodic limb movements, or a parasomnia is suspected. |
Treatment overview
Behavioural treatment comes first and has the most durable benefit; medication is used selectively. The categories below describe available approaches, with any medication choice and dosing set by a prescriber.
Cognitive behavioural therapy for insomnia (CBT-I)
The recommended first-line treatment. It combines stimulus control, sleep restriction, cognitive work on sleep-related beliefs, and relaxation, delivered in person, by app, or online.
Stimulus control
Rebuilding the association between bed and sleep — going to bed only when sleepy, getting up when awake for long periods, and reserving the bed for sleep and sex.
Sleep restriction therapy
Temporarily limiting time in bed to consolidate sleep, then gradually extending it. Uncomfortable at first but among the most effective components.
Sleep hygiene and circadian measures
A consistent wake time, morning light exposure, limiting evening caffeine and alcohol, and a wind-down routine. Useful as support, but not sufficient alone for chronic insomnia.
Prescription medication classes
Includes dual orexin receptor antagonists, melatonin receptor agonists, low-dose sedating antidepressants, and benzodiazepine receptor agonists. Generally intended for short-term or intermittent use with periodic review.
Melatonin and over-the-counter products
Melatonin is mainly useful for circadian timing problems rather than classic insomnia; sedating antihistamines are not recommended for ongoing use, particularly in older adults.
Treating contributors
Addressing sleep apnea, restless legs, pain, depression, anxiety, menopause symptoms, or medication timing often resolves what looked like primary insomnia.
Lifestyle considerations
- Keep the same wake time every day, including weekends — this anchors the body clock more than bedtime does.
- Get bright light within an hour of waking and dim lights in the evening.
- Get out of bed if you have been awake and frustrated for around 20 minutes, and return only when sleepy.
- Stop caffeine at least eight hours before bed, and remember it is in tea, cola, and chocolate too.
- Avoid alcohol as a sleep aid; it shortens sleep onset but fragments the second half of the night.
- Keep the bedroom cool, dark, and quiet, and remove visible clocks.
- Exercise regularly, though vigorous exercise very late may delay sleep in some people.
- Avoid long or late naps if you have trouble sleeping at night.
Prevention
- Protect a consistent sleep and wake schedule, especially during periods of stress.
- Treat short-term insomnia promptly rather than letting compensating behaviours become habits.
- Limit caffeine, nicotine, and alcohol, particularly in the second half of the day.
- Address anxiety, depression, and chronic pain early, since they commonly precipitate insomnia.
- Manage shift work deliberately with light exposure, scheduled sleep, and strategic napping.
- Get snoring or witnessed pauses in breathing evaluated before they fragment years of sleep.
Warning signs and when to get help
Signs that need emergency care
If you believe you are experiencing a medical emergency, call emergency services immediately (911 in the United States).
- Thoughts of harming yourself — call or text 988 in the US for the Suicide and Crisis Lifeline, or call emergency services
- Falling asleep uncontrollably while driving or operating machinery
- Acting out dreams with violent movement causing injury to yourself or a bed partner
Signs that warrant a prompt appointment
These are not emergencies, but they are worth a call to your clinician rather than a wait-and-see.
- Loud snoring, gasping, or witnessed pauses in breathing during sleep
- Persistent daytime sleepiness despite spending adequate time in bed
- Insomnia lasting more than three months
- New or worsening low mood, anxiety, or hopelessness
- Uncomfortable leg sensations at rest that improve with movement
- Reliance on alcohol or over-the-counter sleep aids to fall asleep
Questions to ask a healthcare professional
Take these to your next appointment — or build an agenda with the Appointment Prep tool.
- Could another sleep disorder such as sleep apnea or restless legs be causing this?
- Can you refer me to CBT-I, or recommend a validated digital program?
- Are any of my current medicines affecting my sleep, and could their timing change?
- If we use a sleep medicine, for how long, and what is the plan to stop?
- Would treating my mood, anxiety, or pain improve my sleep?
- Is my sleep schedule mismatched to my body clock rather than truly disordered?
- What should I realistically expect my sleep to look like at my age?
Frequently asked questions
What is CBT-I and why is it recommended before sleeping pills?
CBT-I is a structured short program that changes the behaviours and thoughts keeping insomnia going, using stimulus control, sleep restriction, and cognitive techniques. Trials show it matches medication in the short term and clearly outperforms it afterward, because the benefit persists once treatment ends. See our sleep guide for the components.
How many hours of sleep do I actually need?
Most adults need seven to nine hours, but there is genuine individual variation. The practical test is daytime function: if you wake reasonably refreshed and function well without relying on caffeine, your sleep is probably sufficient regardless of the number.
Does melatonin help insomnia?
Its effect on classic insomnia is modest. Melatonin works best as a timing signal for circadian problems such as jet lag, shift work, or delayed sleep phase. Product quality varies considerably, since supplements are not tightly regulated.
Is it bad to check the clock at night?
Yes, it tends to make things worse. Clock-watching triggers calculation of how much sleep is left and raises arousal at exactly the wrong moment. Turning the clock away or removing it from the room is a small change with a real effect.
Will one bad night hurt my health?
No. Occasional poor sleep is normal and the body compensates. Chronic insufficient or poor-quality sleep is associated with cardiovascular, metabolic, and mental health risks — but anxiety about single bad nights is itself a common driver of insomnia.
Should I nap if I slept badly?
If you have chronic insomnia, generally not — napping reduces the sleep pressure that helps you fall asleep at night. If you must, keep it short, before mid-afternoon, and treat it as an exception rather than a routine.
Sources
- American Academy of Sleep Medicine — Sleep Education — Patient guidance on insomnia and CBT-I
- NHLBI — Insomnia — NIH overview of causes, diagnosis, and treatment
- CDC — Sleep — Sleep duration recommendations and public health data
- MedlinePlus — Insomnia — Consumer summary and related topics
Health Captain links to primary public-health and clinical sources so you can read the original material yourself. See our sources policy.