1. a hormone produced by the pineal gland that regulates sleep and wake cycles
Usage: biological
2. a dietary supplement containing this hormone, used to treat sleep disorders
Usage: medical

Examples

• The body naturally produces melatonin when it gets dark.
• Melatonin levels typically rise in the evening to promote sleepiness.
• Many people take melatonin supplements to help with jet lag.
• The doctor recommended melatonin to help regulate her sleep schedule.
• Exposure to bright light at night can suppress melatonin production.
• She bought melatonin tablets from the pharmacy to help with insomnia.
• Research shows that melatonin can help shift workers adjust to new schedules.