Can't sleep? Why insomnia happens and what actually helps

It is 2 am. Your body is tired, but your mind is busy. You check the time, do the maths on how many hours are left, and feel more anxious. Tomorrow's meeting, the EMI, the argument from yesterday, all arrive at once.

If this happens to you, you are not alone. This article explains why sleep goes wrong, what the guidelines recommend, and when to see a doctor. It is information, not a diagnosis.

What insomnia is

The NHS says insomnia means regularly having trouble sleeping. You may find it hard to fall asleep, wake several times in the night, lie awake, wake too early and not get back to sleep, or not feel rested. The US National Heart, Lung, and Blood Institute describes chronic insomnia as occurring three or more nights a week, lasting more than three months, and not being fully explained by another health problem. The NHS calls insomnia lasting under three months short-term, and three months or longer long-term.

How much sleep do adults need?

The Sleep Foundation says healthy adults need at least 7 hours a night, and most need about 7 to 9 hours. The US CDC gives 7 or more hours for ages 18 to 60, 7 to 9 hours for ages 61 to 64, and 7 to 8 hours for ages 65 and older. Needs vary from person to person, so the number is a guide, not a score to chase.

What a night of sleep looks like

Sleep is not one flat state. The Sleep Foundation explains that a typical night includes four to six cycles averaging about 90 minutes each. Most deep sleep happens in the first half of the night. REM sleep begins around 90 minutes after you fall asleep, and the REM periods get longer through the night.

Why sleep goes wrong

The NHS lists many possible causes of insomnia:

• Stress, anxiety or depression.
• Noise, an uncomfortable bed, or a room that is too hot or cold.
• Alcohol, caffeine, nicotine or other drugs.
• Jet lag or shift work.
• Health conditions, including long-term pain, restless legs syndrome, an overactive thyroid and sleep apnoea.
• Some medicines.

One simple way to think about sleep is the two-process model, first proposed by Alexander Borbely. One force is sleep pressure, which builds while you are awake and falls during sleep. The other is a body clock (circadian) process that does not depend on whether you have been awake or asleep. Together they shape when you feel sleepy and alert.

The NHS advises not napping during the day and not sleeping in after a poor night. These are practical tips rather than part of the model above.

Why worry makes it worse

Worry and sleep can feed each other. The NHS says stress, anxiety and depression are among the most common causes of insomnia. According to the Sleep Foundation, CBT-I includes work on unhelpful beliefs about sleep, such as unrealistic expectations of sleep time and quality, and worry about daytime tiredness.

Shift work is listed by the NHS as a cause of insomnia. If your schedule is fixed, a doctor can help you plan around it.

What helps

CBT-I is the first-line treatment

The American College of Physicians (ACP) 2016 guideline, published in Annals of Internal Medicine, recommends that all adults with chronic insomnia disorder receive CBT-I as the initial treatment. It suggests medicine only be considered, after discussing benefits, harms and costs, for people in whom CBT-I alone was unsuccessful. The NHS says CBT, delivered face to face or through an online self-help programme, may be offered, and that sleeping pills are rarely prescribed.

CBT-I has several parts, according to the Sleep Foundation:

• Stimulus control: keep the bed for sleep. If you cannot fall asleep, or have lain awake for more than about 10 minutes, get up and return only when sleepy. Keep the same wake time every day and avoid daytime naps.
• Sleep restriction: using a sleep diary, your time in bed is set close to the time you actually sleep, then lengthened gradually as sleep improves. It is not recommended for people with conditions like bipolar disorder or seizures, so do it with a professional.
• Cognitive work: changing inaccurate or unhelpful thoughts about sleep.
• Relaxation: such as slow breathing, progressive muscle relaxation or meditation.

CBT-I often takes six to eight sessions. The Sleep Foundation says that with multicomponent CBT-I, 70% to 80% of patients with primary insomnia improve, and the gains often last. Digital CBT-I appears similar to in-person care, though few studies compare them directly.

Sleep hygiene: useful, but limited

Sleep hygiene means everyday habits that support sleep. The Sleep Foundation says it "isn't a panacea": it may help, but it will not always fix sleep problems, and people with serious insomnia or conditions like sleep apnoea usually need other treatment too. Habits worth trying:

• Get up at the same time each day.
• Limit caffeine in the afternoon and evening. The NHS says to avoid caffeine, alcohol and nicotine for at least 6 hours before bed.
• Avoid large, late meals. This matters in homes where dinner is late.
• Keep a wind-down time before bed. The Sleep Foundation suggests a 30 to 60 minute break from screens.
• Keep the bedroom dark, quiet and a comfortable temperature.
• Avoid vigorous exercise in the 4 hours before bed, and do not nap during the day (NHS).

The Sleep Foundation says screen light "may" decrease melatonin, so the evidence for some of these tips is less certain than the general advice.

Be careful with sleep aids

The NHS says GPs rarely prescribe sleeping pills, usually for a few days or weeks at most and only if insomnia is severe and other treatments have not worked, because of the risk of serious side effects and dependence. Please speak to a doctor before using any sleeping pill, herbal product or supplement. Do not start one on your own.

Myths about sleep

• "I must sleep 8 hours or I will fall sick." Needs vary, and the guides give ranges.
• "Sleeping in on the weekend fixes it." The NHS advises against sleeping in after a bad night, and the Sleep Foundation suggests a fixed wake time.
• "Alcohol helps me sleep." The NHS lists alcohol as something to avoid near bedtime, and as a possible cause of insomnia.
• "One bad night means I have insomnia." Insomnia means regular trouble sleeping. Short-term trouble is common.

When to see a doctor

The NHS says to see a GP if changing your habits has not helped, if trouble sleeping has lasted months, or if it makes daily life hard to manage. A doctor will look for the cause. They may refer you to a sleep clinic if another condition is suspected.

Poor sleep can also be a sign of low mood or anxiety, so tell your doctor how you have been feeling in general.