Best-known as a sleep-inducing supplement, melatonin has some surprising benefits.

Known as N-acetyl-5-methoxytryptamine, melatonin is an indoleamine neurotransmitter, which is synthesized from the essential amino acid tryptophan and secreted by the pineal gland (in the brain). Melatonin synchronizes the body's internal clock (or circadian rhythms) and is released in abundance at night or in states of darkness. Because of its connection with light/dark cycles and the fact that it can help induce sleep (when taken before bed), most people consider melatonin supplements only when they are trying to combat jet lag or insomnia.

However, studies show that melatonin supplementation provides myriad health benefits beyond promoting sleep, including increased antioxidant activity, antiinflammatory characteristics, immunity support, anti-cancer activity, cardiovascular protection, diabetes and obesity prevention, neuroprotection, and anti-aging activity. With this laundry list of benefits, it's no wonder scientists have been studying melatonin as a performance-enhancing supplement.

Melatonin and growth hormone

Growth hormone (GH) is released during sleep and exercise recovery to promote muscular repair and growth and increased lipolysis (aka fat burning). After intense exercise, your body prepares its internal envionment for recovery, and this includes increasing the release of hormones like GH, which promote increased anabolism. Studies have shown that taking melatonin before training will not make you feel sleepy during your workout but that it will augment GH release around the workout window. For example, one study showed that taking 5 milligrams of melatonin one hour before completing a short bout of moderate-intensity cycling exercise resulted in a 72 percent increase in peak GH release when compared to exercising after taking a placebo. A more recent study from Baylor University reported that trained males who were given 5 milligrams of melatonin one hour before a leg workout had a doubling of GH levels before and after training compared to subjects who received a placebo. In fact, the researchers reported that subjects who took only 0.5 milligrams of melatonin had higher GH levels after training.

GH secretion (like melatonin) is tuned to the body’s circadian rhythms. On rest days, the greatest surge of GH from the anterior pituitary occurs at the onset of slow wave/deep sleep. Interestingly, studies have shown that taking up to 5 milligrams of melatonin (without daily exercise) before sleep or during wakeful hours results in increased blood GH levels. This is mainly because melatonin decreases the secretion of a hormone called somatostatin (or growth hormone–inhibiting hormone). Somatostatin normally decreases GH secretion, so when it is “blocked” by melatonin, GH secretion goes up.

Melatonin as an antioxidant

Heavy training can independently promote the production of free radicals, like reactive oxygen species (ROS), leading to increases in oxidative stress. The body adapts to this "oxidative insult" by upregulating its enzymatic antioxidant defense system during exercise recovery, which improves the efficiency of the body's antioxidant defense system and protects cells against oxidative damage during subsequent exercise bouts. Notably, high levels of ROS lead to strenght loss and muscular fatigue during prolonged and intense exercise. This delicate balance between beneficial and harmful effects of ROS is fundamental to physiological function, health and exercise adaptations.

Research clearly shows that melatonin is one of the body's most potent antioxidants, with about twice the capacity as vitamin E to buffer ROS, which synergizes with the body's antioxidant pool to improve its overall activity. In support, a study conducted at the University of Seville Medical School in Spain illustrated that taking either 6 milligrams of melatonin or a placebo 30 minutes preworkout increases blood total antioxidant activity and decreases exercise-induced oxidative stress. As a bonus, athletes who took melatonin had increased fat metabolism during training and overall improvements in immunity.

Melatonin and inflammation

Beyond increases in oxidative stress, long and intense exercise bouts signal the body to release inflammatory cytokines (small proteins) that promote muscle damage and lead to muscle soreness. A study published in the Journal of Pineal Research examined whether pre-training melatonin supplementation would improve the oxidative and inflammatory responses associated with intense training. In this study, a group of highly trained endurance athletes were given a melatonin supplement or placebo for three days before completing an intense 50-kilometer uphill run in the Sierra Nevada (in Granada, Spain). At the end of the study, the authors concluded that oral supplementation of melatonin during high-intensity exercise is efficient in reducing oxidative stress and markers of inflammation. In all, such improvements in the muscular microenvironment protect muscles from damage, thereby potentiating training adaptations.

How to supplement melatonin

So, by now, it should be obvious that melatonin is a great supplement to take during training and rest days to improve oxidative status, augment GH release and promote restorative sleep at night. Based on past and current literature, the best way to supplement melatonin and take advantage of all its positive effects is to take 0.5 to 5 milligrams 30 to 60 minutes before training and 0.5 to 5 milligrams immediately before hitting the sack. On rest days, take the preworkout dose at the same time as you would on training days.