Why melatonin is not the whole sleep story

Walk into any pharmacy and you will find shelves of melatonin promising a shortcut to better sleep. Melatonin does a real job, but it is one part of the process, and not the part that keeps you asleep.

Melatonin is a signal, not a sedative

Melatonin is a hormone produced by the pineal gland when your brain senses darkness. Its role is timekeeping: telling your body that it is night.

• It helps you fall asleep by lowering body temperature and easing the nervous system toward rest.
• Its half life is short, roughly 30 minutes to two hours, so it wears off quickly.

It is the starter's pistol at the beginning of a race, not the thing that carries you to the finish line. That is why people who take melatonin often fall asleep quickly and still wake during the night.

What actually keeps you asleep

• Adenosine builds through the day and creates the sleep pressure that sustains rest.
• GABA quietens brain activity and reduces unnecessary wake ups.
• Sleep cycles of light, deep and REM sleep are governed by the circadian rhythm, the roughly 24 hour internal clock.
• Environment, meaning darkness, quiet and a temperature around 18 to 20 degrees Celsius, or 65 to 68 Fahrenheit.

Why more melatonin is not the answer

Melatonin has documented uses, particularly for jet lag and shift work. For most people, though, poor sleep does not come from a melatonin shortage. The usual causes are modern and behavioural:

• Blue light at night suppresses natural melatonin production.
• Stress raises evening cortisol, which works against sleep.
• Irregular bedtimes confuse the circadian rhythm and fragment sleep.

The bigger picture

Sleep is not controlled by a single hormone. It is a process involving neurotransmitters, hormones, body temperature and brain activity working together. Melatonin may open the door. Your own rhythms and the environment you build are what keep you there.

If you want the practical version, we have written up the habits that make the most difference.