Causes of insomnia: stress, habits, hormones and why it lingers

CareOps editorial team · October 24, 2026 · 9 min read

Mental wellness information and service guidance published by CareOps.

You're tired, yet as soon as you lie down you feel wide awake, or you finally fall asleep only to wake before dawn and stay awake. Search for the cause and you'll find stress, coffee, phones and hormones all named. In practice insomnia usually comes from several things overlapping, and it often continues after the first trigger is gone. Let's separate why sleep starts to slip from why it keeps slipping.

What is insomnia? Start with the symptoms #

The UK's National Health Service (NHS) describes insomnia as regularly having problems sleeping: finding it hard to fall asleep, waking several times in the night, waking early and not getting back to sleep, still feeling tired after waking, and feeling tired, irritable or unable to concentrate during the day. Insomnia lasting less than 3 months is called short-term, and 3 months or longer is long-term. That's different from one or two rough nights.

What causes insomnia? Three groups of factors #

Sleep researchers Spielman and colleagues (1987) described insomnia as a process in which three kinds of factors build up, often called the “3P model.” Rather than hunting for a single cause, sorting which factors overlap in your sleep right now shows where to start.

A review by Riemann and colleagues (2010) takes a similar view: a vulnerability in the balance between arousal and sleep meets psychological or physical stress, and sleep-related behaviors, a learned link between bed and wakefulness, and worry or rumination keep insomnia going.

Stress and insomnia: why does tension keep you awake? #

To fall asleep, body and mind need to loosen a little. Under stress, the body leans toward staying alert, as if something still needs doing. The review by Riemann and colleagues gathered studies showing that people with insomnia have higher arousal not only at night but also during the day, and calls this “hyperarousal.” That's how you can feel exhausted yet wide awake once you lie down. For ways to ease tension during the day, see our guide to stress relief.

Which everyday habits can cause insomnia? #

Many of the common causes the NHS lists are everyday habits and the sleep environment. Each looks small, but together they can unsettle sleep.

• Caffeine, alcohol and nicotine: the NHS suggests avoiding alcohol, tea and coffee for at least 6 hours before bed. Alcohol can feel like it helps you drift off, yet it's listed as a cause of poor sleep. If you often drink to sleep, try the drinking habit self-check.
• An irregular sleep schedule: when bedtimes and wake times shift from day to day, the body's rhythm drifts. Shift work and jet lag cause insomnia for the same reason.
• Naps and catch-up sleep: sleeping during the day or making up for it at the weekend leaves less sleep pressure for the night.
• Screens right before bed: using a phone or watching TV just before sleep can leave you more awake.
• The sleep environment: noise, a room that's too hot or cold, and an uncomfortable mattress or pillow are common causes too.

If you naturally get sleepy later, forcing an early bedtime can make sleep harder. You can gauge your rhythm with our morning or evening type guide.

Hormones and the body: can menopause cause insomnia? #

Yes, changes in the body can cause insomnia too. The NHS lists hormone-related changes such as menopause and an overactive thyroid, long-term pain, restless legs syndrome, snoring or interrupted breathing during sleep (sleep apnoea), conditions such as Alzheimer's or Parkinson's disease, and many medicines as possible causes. These rarely settle with habit changes alone, so getting them checked by a doctor comes first. If a medicine seems to affect your sleep, don't stop it on your own; talk with the doctor who prescribed it.

The mind: do anxiety, depression and insomnia affect each other? #

Stress, anxiety and depression are the first causes of insomnia the NHS lists, and the influence runs both ways. In a meta-analysis of 21 longitudinal studies by Baglioni and colleagues (2011), people without depression who had insomnia had about twice the risk of later developing depression compared with people without sleep problems. Worry keeps you awake, and poor nights feed worry and low mood, so a loop forms easily. If thoughts start racing as soon as you lie down, see when your thoughts race as you try to sleep.

Why does insomnia continue after the cause is gone? #

Sometimes the exams end and work settles down, yet sleep doesn't come back. In the 3P model, what remains are the perpetuating factors. Going to bed early or lying in late to make up for lost sleep increases the time you spend awake in bed, and the body learns that “bed = a place to toss and turn.” Watching the clock, counting the hours left and worrying “what if I can't sleep again tonight?” chases sleep away once more. Whatever the original trigger was, breaking this loop is the work to do now.

Where to start with insomnia #

1. Track your sleep for a week: each morning, roughly note when you went to bed, when you think you fell asleep, how often you woke and when you got up. Our sleep diary guide and free template shows how.
2. Keep a similar wake-up time: even after a bad night, not shifting your wake time much helps the rhythm recover.
3. Go to bed when sleepy, and step out when frustrated: if lying there makes you more alert, get up when it's safe to, rest quietly somewhere else and return when sleepy.
4. Write worries down in the evening: an hour or two before bed, note what's on your mind and one small step for tomorrow, so it's easier to set the thoughts aside in bed.

If insomnia lasts more than a few weeks, it's worth knowing about cognitive behavioral therapy for insomnia (CBT-I), which combines these steps into a structured approach. The American College of Physicians (ACP) recommends CBT-I as the first treatment for chronic insomnia in adults. Sleep restriction, which shortens time in bed, can increase daytime sleepiness, so plan it with a professional rather than alone. See what is CBT for insomnia (CBT-I)? for details.

How much is insomnia affecting you? The Athens Insomnia Scale #

The Athens Insomnia Scale (AIS) uses eight questions to look at falling asleep, night waking, early waking and sleep quality, along with daytime mood, functioning and sleepiness. You can take it right away without logging in.

If you'd like help untangling the thoughts and habits behind your sleep #

CareOps Maeumi is an AI counseling app that runs sessions with approaches such as cognitive behavioral therapy (CBT) and acceptance and commitment therapy (ACT) and remembers past sessions so the next one picks up where you left off. If sleep is a concern, you can choose CBT for insomnia (CBT-I) as your course, and then a sleep diary, a simple version of stimulus control and working with thoughts about sleep happen inside the conversation. Get the app

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