Melatonin ranks as the most popular sleep aid potentially assisting those with jet lag, disordered sleep due to shift work, rotating schedules and even simple insomnia. Levels of this natural hormone are manufactured by the pineal gland as the sun goes down. Concentration peaks during the hours following midnight and vanishes as the sun rises.
Melatonin allows synchronization of the body clock to a 24 hour day. In totally blind individuals and those living experimentally in complete darkness the day averages about 24.5 hours which significantly disrupts the sleep wake cycle.
LED light produces excessive quantities of blue light as exemplified by computer screens, iPads, laptops and ebook readers. These delay production of melatonin and interfere with sleep. Incandescent light bulbs lack these troublesome wavelengths of light.
Recent investigations suggest a more widespread but still undefined role of melatonin than previously assumed. It appears synthesis occurs in most tissues with potential implications for fertility, cancer, psychiatric disease and blood pressure control. It may function as an anti-inflammatory agent, modulate pain and protect the tissues from oxidants.
Interestingly its ability to induce sleep and correct circadian disorders due to shift work and jet lag remain relatively weak.