Insomnia: when the mind won't switch off at night

Two in the morning. The body is tired, but the mind is running as if it were midday: a conversation with a manager, an unpaid bill, something said to someone a week ago. The person turns over, checks the phone (four and a half hours until the alarm) and starts working out how much sleep is still possible. That calculation is what finally chases sleep away.

Everyone has a night or two like this, especially under stress. Chronic insomnia is the word for sleep problems that return several times a week for three months and affect daytime life, even though there is the chance to sleep. According to the European guideline on the diagnosis and treatment of insomnia published in 2023, this kind of insomnia affects up to 10% of adults in Europe.

Why the mind won’t switch off

Sleep is an involuntary process. It can’t be switched on by willpower; it can only be given the right conditions. Insomnia is largely kept going by the ways a person, without noticing, undoes those conditions. The result is a trap with several parts.

The nervous system stays in daytime mode. In people with long-term insomnia, research finds raised arousal both day and night: in heart activity, hormones and brain activity. The body behaves as if it isn’t yet safe to relax.

The thoughts turn to sleep itself. At first a person can’t sleep because of their worries; later, because of worry about not sleeping: “if I don’t get to sleep, tomorrow will be a disaster”, “here we go again”. The psychologist Allison Harvey, then working at Oxford, described how this kind of worry about sleep and its consequences creates tension that makes sleep even harder.

The bed becomes linked with being awake: when night after night is spent tossing and turning, the brain starts to associate the bed with tension rather than sleep. Many people notice something odd: they nod off on the sofa in front of the TV, but the moment they get into bed, they are wide awake.

The harder the effort, the worse it gets: trying to force sleep, lying perfectly still and pushing thoughts away all raise tension. Sleep researchers in Glasgow see this effort as one of the mechanisms that keep insomnia going.

The clock adds fuel to the fire: in a 2007 experiment, people asked to watch a clock before sleep became more worried, took longer to fall asleep, and those with insomnia overestimated even more how long it took them to fall asleep.

Why people wake at 3am

Sleep runs in cycles of roughly an hour and a half. The first half of the night holds more deep sleep; towards morning, sleep becomes lighter. Brief awakenings at that time are normal and usually not even remembered. But for someone who is tense, a minute of being awake is enough for the mind to switch on again, and then sleep may not return before morning.

Night-time awakenings become more frequent with age. Alcohol plays a part too: it helps people fall asleep faster but disrupts sleep more in the second half of the night. That is why a glass of wine “to help sleep” can end in waking in the early hours.

Caffeine, nicotine and the phone

Caffeine leaves the body slowly: it takes 3–7 hours to clear just half a dose, and noticeably longer with hormonal contraception or in pregnancy. In one study, a large dose of caffeine (about what is in a large coffee-shop coffee) taken six hours before bed cut sleep by more than an hour on objective measures, even though the participants themselves barely noticed. An ordinary cup during the day has a much smaller effect: what matters most is the dose.

Nicotine is a stimulant. Smokers on average fall asleep later and sleep more lightly, and in people who are heavily dependent, falling nicotine levels at night can wake them with an urge to smoke. When someone quits, sleep can get worse for a few weeks: this is part of nicotine withdrawal, and it passes with time.

The phone. Screen light itself delays sleep only slightly: in laboratory studies the difference was a matter of minutes, and in one experiment a phone’s night mode did not improve sleep. Something else has a bigger effect: an absorbing feed pushes bedtime later, and the habit of picking up the phone in bed when sleep won’t come strengthens the link between the bed and being awake.

What helps

The key is to stop fighting for sleep and remove what keeps it away. Much depends on what a person does in the evening, at night and in the morning.

In the evening

Deal with worries before bed. An hour or two before sleep, it can help to write down everything on the mind and, next to each worry, one next step: “call the bank”, “ask the doctor”. In a small study of students with insomnia, this kind of exercise reduced racing thoughts before sleep. In another, with healthy young adults, five minutes before bed spent writing a detailed to-do list for the coming days helped them fall asleep faster than writing about tasks already done. The point is to give worries their own time and place – and that time is not the middle of the night.

Don’t go to bed before feeling sleepy. After a bad night it is tempting to go to bed early “to catch up”. But extra time in bed usually turns into extra time awake.

In bed at night

Stop trying to sleep: sometimes it helps to simply allow oneself to lie and rest, without demanding sleep. When “I must sleep” stops being the task, some of the tension goes with it.

Put the clock out of sight: no checking the time, whether on an alarm clock or a phone. Knowing it is 3:40 changes nothing, but it starts the counting and the worry.

Get up if sleep won’t come: if frustration is building and it is clear that sleep isn’t happening, it is better to get up, go to another room with dim light and do something calm, then go back to bed when sleepiness returns. It is best to go by how it feels rather than by the clock. This way the bed gradually becomes linked with sleep again, not with a struggle for it.

Give the mind calm images: if thoughts keep going round in circles, it can help to picture a calm, pleasant scene in detail (a walk through familiar places, a holiday) with its colours, sounds and small details. In a study of people with insomnia, absorbing imagery like this helped them fall asleep faster.

In the morning and during the day

Get up at the same time after every night. Even after a bad one. A fixed wake-up time keeps the body’s rhythms steady and helps sleepiness build up by the next evening. The first days are hard, but this is how sleep gradually settles.

Don’t sleep in: long lie-ins and daytime naps “for last night” upset the rhythm and take sleep away from the next night. The exception is when sleepiness is dangerous, for example before a long drive: then a short rest is safer.

Remember that the day often goes better than it seems at night: people with insomnia tend to overestimate how little they slept and how badly they will function. That doesn’t make lost sleep pleasant, but it removes some of the panic that itself keeps sleep away.

There is also a stricter approach: cutting time in bed down to roughly the time actually spent asleep, then gradually extending it. It works well, but in the first weeks it increases daytime sleepiness and doesn’t suit everyone: for people with epilepsy or conditions made worse by sleep loss (bipolar disorder, for example) it can be risky. It is best done with the support of a specialist rather than alone.

Insomnia, depression and anxiety

Insomnia is not always a problem in its own right; it can also be one of the signs of depression or an anxiety disorder, where disturbed sleep is among the symptoms. According to NICE, the UK’s clinical guidance body, about half of people diagnosed with insomnia also have another mental health condition, and around 70% of people with depression have insomnia.

The link works the other way too: insomnia itself roughly doubles the risk of depression, according to a 2011 meta-analysis of 21 studies.

So when poor sleep comes with persistent low mood, a loss of interest in things that used to bring pleasure, or constant anxiety, it matters to look beyond sleep. Sometimes sleep only settles once the depression or anxiety itself is treated, and insomnia that drags on for months shouldn’t be treated as a minor thing.

When and where to get help

If insomnia lasts for months and gets in the way of normal life, it is worth getting help. Who to turn to depends on what lies behind it.

• A GP: if sleep may be disrupted by an illness, medication or alcohol, or if there is loud snoring with pauses in breathing during sleep. This may be sleep apnoea. If sleep apnoea or another sleep disorder is suspected, a GP can refer someone to a sleep clinic.
• A psychiatrist: if it looks like depression or an anxiety disorder. They make a diagnosis and choose treatment, usually medication.
• A psychotherapist: if a psychiatrist has recommended psychotherapy, or if there is no disorder but a lot of worry, emotional strain and stress.

Sleep rarely comes back in a single night, and the first weeks of change are often hard. But insomnia is well understood, and there are ways to help: some that a person can try on their own, and some that need the support of specialists. What matters most is not to stay alone with it for long.