A Multitasking Molecule

Melatonin is a lot like the tulip. In the mid-17th century, the beautiful bulbs inspired the world’s first speculative bubble, much as the hormone reached star status in the mid-1990s as a substance that could do everything from mitigate jet lag (it can) to reverse aging (it can’t). “Melatonin Madness,” neuroscientists dubbed it, because the hormone’s biologic role was still a mystery. Now, as a result of growing research, they know that the substance not only induces sleep but keeps the brain in order as well.

Melatonin is released by the pineal gland, a small structure in the brain, when darkness falls—signaling to the body that it’s time to rest. Levels remain high throughout the night and decline during the daylight hours. The daily rise and fall of the hormone helps regulate our internal clocks, and its nocturnal activation has earned it the moniker “the Dracula hormone.”

Highly responsive to environmental conditions, the circadian rhythms incited by melatonin influence many bodily functions, from alertness to body temperature to hormone production. Thrown out of whack by travel between time zones or night shift work, the body’s internal timer can undermine performance or create feelings of malaise.

Melatonin supplements have long been used as an alternative to counting sheep. Taken shortly before one’s anticipated bedtime, they mimic the body’s natural rise in the hormone. Supplementation has been shown to help people who need to move their internal clock forward or back—those adjusting to a new time zone, shift workers on graveyard duty.

Research now suggests that melatonin may do more than help you get a good night’s rest; it helps brain function, too. The hormone is a potent antioxidant. Studies show that by minimizing oxidative stress and inflammation, it acts as a neuroprotectant, reducing damage from stroke and traumatic brain injury.

Melatonin production drops dramatically with age, which is thought to explain why insomnia is so common among the elderly. The waning of melatonin may also figure into age-related disorders like Alzheimer’s and Parkinson’s disease. People over 80 have half as much melatonin in their cerebral spinal fluid as younger people, and those with Alzheimer’s disease have just one-fifth as much. Studies show that melatonin counters the neurotoxic effects of amyloid beta and tau proteins, which accumulate in Alzheimer’s patients, and that it slows the progression of cognitive impairment.

Researchers also find the hormone of value as an antidepressant. Seasonal affective disorder (SAD) is a form of depression common during the winter months, thought to be the effect of a yawning mismatch between one’s normal sleep-wake cycle and the shifting light-dark cycle. “It’s like having jet lag for five months,” says Alfred Lewy, head of the Sleep and Mood Disorders Lab at Oregon Health & Science University. For some, the rhythm mismatch depresses mood.

SAD can be readily treated. Lewy has found that low doses of melatonin and bright light therapy, appropriately timed, realign the sleep-wake cycle and alleviate symptoms of SAD.

Shifting the body clock may also help people suffering from nonseasonal, or major, depression. Researchers have long known that the vast majority of depressed people experience insomnia; addressing their sleep problems, many believe, may alleviate depressive symptoms.

A synthetic version of melatonin is proving as effective as commonly prescribed antidepressants, including Prozac, but without many of the side effects. Targeting the circadian system restores sleep as well as boosts mood.

Researchers are still exploring just how multifaceted melatonin is. Studies show it may help protect the heart. And because insulin secretion is synchronized to melatonin production, the sleep-wake hormone may even be of use in metabolic conditions such as diabetes.

Melatonin in the Brain

• Reduces neurodegeneration caused by amyloid beta and tau proteins
• Fights seasonal affective disorder
• Combats depression
• Acts as potent antioxidant by inhibiting production of free radicals
• Lowers risk of stroke and resulting impairment
• Minimizes brain swelling from traumatic head injury

A Hormone for All Seasons

• Acts as free-radical scavenger
• Inhibits growth of breast tumors
• Regulates sleep-wake cycle
• Helps regulate insulin secretion
• Influences estrogen release

A Melatonin Medley

• Melatonin is naturally produced by the pineal gland during the evening in response to diminished daylight.
• Melatonin levels typically begin to rise around 8 P.M., spike at 3 A.M., and drop soon thereafter.
• Very few foods contain melatonin, although cherries are richest in the substance.
• Melatonin readily passes through the blood-brain barrier, making it effective in protecting brain cells against oxidative stress.
• Blue light, such as that emitted from smartphones and tablets, suppresses melatonin production; fiddling with your phone at night suppresses sleep.
• Melatonin influences the start of
• menstruation.
• Insomnia in the elderly is attributed to the dramatic decrease of melatonin production with age.

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