📚 Part of our Sleep & Stress Guide — an evidence-based guide.
Insomnia is not simply “not sleeping enough.” It is difficulty falling asleep, staying asleep, or waking too early despite adequate opportunity — and it causes daytime consequences: fatigue, poor concentration, irritability, low mood. Someone who sleeps five hours and feels fine does not have insomnia. Someone who lies awake for two hours nightly and drags through the day does, regardless of the total.
That distinction matters because it points at what actually maintains the problem, which is usually not the thing that started it.
The most useful model: what starts it is not what keeps it going
Sleep researchers describe insomnia in three parts, and this framework explains more than any list of causes.
Predisposing factors are the traits you bring — a tendency toward anxiety, a light-sleeping constitution, being female, being older, family history.
Precipitating factors are what triggered this episode: a bereavement, a stressful job period, illness, a new baby, a schedule change.
Perpetuating factors are what keeps it going after the trigger has passed — and these are almost always behavioral. Going to bed earlier to “catch up.” Lying in bed awake for hours. Sleeping in on weekends. Napping. Anxiously monitoring the clock. Trying harder to sleep.
This is the key insight: the stressful project ended months ago, but the insomnia continues, because the coping behaviors have become the cause. Treating insomnia effectively means dismantling the perpetuating factors, not resolving the original trigger.
How the loop forms
Sleep drive builds the longer you are awake. Spending ten hours in bed to get six hours of sleep dilutes that drive across too many hours, guaranteeing fragmentation. Meanwhile, repeatedly lying awake in bed teaches your brain to associate the bed with alertness and frustration — a genuine conditioned response, which is why so many people with insomnia feel sleepy on the sofa and wide awake the moment they get into bed.
Then anxiety about sleeping compounds it. Worrying about not sleeping produces arousal, which prevents sleep, which justifies more worry. Insomnia becomes self-sustaining.
The everyday contributors
Irregular schedules. Inconsistent wake times keep the circadian system unable to anchor (why regularity matters).
Caffeine, whose half-life is longer than most assume — an afternoon coffee reduces deep sleep even when you fall asleep normally (how late is too late).
Alcohol, which speeds sleep onset and then fragments the second half of the night as it clears — a common cause of reliable 3 a.m. awakenings.
A warm bedroom, which blocks the temperature drop sleep requires (the science), and too little morning light, which leaves the clock unanchored (why it works).
Medical and psychiatric causes worth ruling out
Sleep apnea frequently presents as insomnia rather than snoring, particularly in women. Loud snoring, gasping, morning headaches or waking unrefreshed all point toward it, and it will not respond to sleep hygiene (warning signs).
Depression and anxiety have a bidirectional relationship with insomnia — each worsens the other, and early morning waking is a classic feature of depression. Restless legs syndrome produces an urge to move the legs that worsens at rest and is often mistaken for ordinary difficulty settling. Chronic pain, an overactive thyroid, reflux, and nocturia all fragment sleep. Perimenopause is a very common and under-discussed cause in women in their forties and fifties.
Medications matter too: some antidepressants, stimulants, steroids, beta blockers, thyroid replacement and decongestants all disrupt sleep. If insomnia began within weeks of a new prescription, that is worth raising.
The treatment that works, and it is not a pill
The recommended first-line treatment for chronic insomnia is cognitive behavioral therapy for insomnia (CBT-I) — not medication. It outperforms sleeping pills over the long run, and its benefits persist after treatment ends, which is not true of drugs.
Its main components are specific and somewhat counterintuitive:
Sleep restriction — the most powerful and least intuitive part. You temporarily limit time in bed to roughly the hours you actually sleep, which concentrates sleep drive and consolidates fragmented sleep. Time in bed is then extended gradually as efficiency improves. It is uncomfortable for the first week or two and it is the component that does the most work.
Stimulus control — rebuilding the bed-sleep association. Bed is for sleep only. Get up after roughly 20 minutes of wakefulness, go elsewhere, do something dull in dim light, return when sleepy. Repeat as needed (more tactics).
Cognitive work on the beliefs that fuel arousal — particularly catastrophic thinking about the consequences of a bad night.
Relaxation, where slow breathing has direct physiological effects (cyclic sighing).
CBT-I is available through therapists and through validated digital programs, which matters given how few clinicians offer it. Ask your doctor specifically for it by name — many people are never told it exists.
What about sleeping pills and melatonin?
Prescription hypnotics have a legitimate short-term role, particularly for acute insomnia around an identifiable stressor. Their limitations are real: tolerance, dependence, next-day impairment, and higher fall risk in older adults. They are not a long-term solution, and they do not resolve the perpetuating factors.
Melatonin is a timing signal rather than a sedative. It helps circadian problems — jet lag, shift work, a sleep phase that runs late — and produces only a small effect for insomnia proper (what the evidence shows).
When to see a doctor
See a doctor if difficulty sleeping occurs at least three nights a week for three months or more, if daytime sleepiness affects driving or work, if you snore loudly or gasp at night, if insomnia comes with low mood or thoughts of self-harm, or if it began soon after starting a medication. Ask specifically about CBT-I, and do not start or stop prescription sleep medication on your own.
The honest bottom line
Insomnia is usually maintained by the things people do to cope with it — extra time in bed, lying awake, catching up on weekends, trying harder. That is genuinely good news, because those are changeable. Fix the schedule and the bed association first, rule out apnea, depression, restless legs and medications, and ask for CBT-I by name. The trigger rarely needs to be resolved for the insomnia to lift; the loop does.
If you take melatonin long term, the recent heart failure headline is worth reading properly.
Frequently asked questions
What is the most common cause of insomnia?
Stress and anxiety are among the most common triggers, along with irregular sleep schedules, caffeine or alcohol, screen use at night, and underlying conditions like sleep apnea, pain, or depression.
How do you fix insomnia?
The most effective treatment is CBT-I (cognitive behavioral therapy for insomnia), which addresses the habits and thoughts that keep you awake. Good sleep habits, a consistent schedule, and limiting caffeine also help.
What is the best treatment for chronic insomnia?
CBT-I is the recommended first-line treatment — it works better than sleeping pills in the long run and without the side effects. See a doctor if insomnia is persistent.