Melatonin is a hormone made in the body. It regulates night and day cycles or sleep-wake cycles.
Darkness triggers the body to make more melatonin, which signals the body to sleep. Light decreases melatonin production and signals the body to be awake. Some people who have trouble sleeping have low levels of melatonin. It's thought that adding melatonin from supplements might help them sleep.
People most commonly use melatonin for insomnia and improving sleep in different conditions, such as jet lag. It is also used for depression, chronic pain, dementia, and many other conditions.

• Appearance: White to off-white powder
  
• Solubility: Soluble in ethanol to at least 50mg/ml