What is melatonin?

The pineal gland, a small pea-shaped gland in the brain, releases melatonin in the evening as light fades, peaking in the middle of the night. It tells the body it is night-time rather than knocking you out like a sleeping pill. Bright light, especially blue light from screens, can suppress it, which is one reason late-night phone use may disrupt sleep. Melatonin supplements are used for jet lag and some sleep disorders; in the US they are sold over the counter, while in the UK and much of Europe they generally require a prescription. Melatonin production tends to decline with age.