Causes of insomnia: seven groups to review

Why treating the original cause is usually not enough

This is the most important point on the page. Insomnia usually starts with something specific: a stressful period, an illness, a loss, a trip across time zones. But a few months later, that event may be long past while sleep has still not returned.

The reason is that during the insomnia, people develop very natural coping responses: going to bed earlier for more chance of sleep, lying in longer in the morning, napping in the day, monitoring their sleep closely. Each is reasonable. All four make the problem worse, and they are what is now keeping the insomnia going.

The seven groups

The most overlooked group: current medication

In practice this is the group that pays off fastest when found, and also the one fewest people think of. A great many commonly used medicines can cause insomnia: some blood pressure drugs, corticosteroids, asthma medication, activating antidepressants, over-replaced thyroid medication, painkillers containing caffeine, and cold remedies with a decongestant.

The most useful clue is timing: if the insomnia started within a few weeks of a new medicine or a dose increase, say so to your doctor. Do not stop anything yourself, as abrupt withdrawal carries its own risks for many drugs.

Three substances everyone uses

• Caffeine has a half-life of around 5 hours in adults, but it varies greatly between people. A coffee at 3pm still leaves roughly half of its caffeine in your blood at 8pm.
• Alcohol shortens the time to fall asleep, so it is easily mistaken for a sleep aid, but it fragments the second half of the night and reduces REM sleep. Sleep after drinking is less restorative.
• Nicotine is a stimulant. Smoking in the evening makes falling asleep harder, and falling levels overnight can cause awakenings.

How to review this yourself over two weeks

Most of the causes in the table above are found by systematic observation, without any tests. The most effective method is two weeks of a sleep diary that also records the factors you suspect.

1. Each morning record: time into bed, how long until sleep, how many awakenings, final wake time, time out of bed, and a self-rated sleep quality from 1 to 5.
2. Also record during the day: when you had coffee and tea, alcohol, tobacco, when you exercised, whether you napped and for how long.
3. After two weeks, rank the nights by quality and look at the five worst. Which factor appears there that does not appear in the five best?
4. Compare weekdays with days off. If weekends are clearly better and you get up much later, think about circadian rhythm rather than insomnia.

When several causes are present at once

This is more common than not. Someone may be drinking coffee in the afternoon, working under stress, taking a blood pressure medicine that causes insomnia, and have developed the habit of spending three hours in bed awake each night.

In that situation, dropping the coffee, seeing no improvement, and concluding "so coffee was not the cause" is faulty reasoning. It may be one of four causes, and removing one of four is not enough to see a difference. This is why interventions are applied as a package rather than tried one at a time.