Melatonin

What it is

Melatonin is the hormone the pineal gland releases as evening light fades, and it acts on receptors in the brain that set the timing of the sleep–wake cycle. Taken as a supplement it signals the body clock that night has begun rather than sedating in the way a sleeping pill does. It is used over the counter for insomnia and general sleep support.

Used for

• Insomnia
• Sleep support

What to know while taking it

It is taken close to bedtime, since its effect depends on when it is taken as much as on how much. Bright screens and room light afterwards work directly against it, so keeping the lights low preserves the signal. It can leave drowsiness or slowed reactions, which matters for driving or operating machinery that evening and the following morning. It is intended for short courses rather than indefinite nightly use.

When to see a doctor

Insomnia that persists after a short course, or that comes with daytime exhaustion, low mood or breathing pauses during sleep, is worth seeing a doctor about instead of continuing on one's own.

Worth knowing

• Care when driving
• Keep the lights low afterwards
• Short courses only