MELATONIN

By Dwayne N. Jackson, PhD

Known among science nerds 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. Due to 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 combat jet lag or insomnia. However, many studies show that melatonin supplementation provides many health benefits beyond promoting sleep, including increased antioxidant activity, anti–inflammatory characteristics, immunity support, anticancer activity, cardiovascular protection, anti–diabetic, anti–obese, neuroprotection, and anti–aging activity. With this laundry list of benefits, it’s no wonder supplement scientists have been studying melatonin as a performance enhancing supplement. 

Melatonin and growth hormone (GH)

Growth hormone (GH) is an important factor released during sleep and exercise recovery to promote muscular reapair/growth and increased lipolysis (a.k.a., fat burning). After intense exercise, your body prepares its internal environment for recovery, this includes increasing the release of hormones like GH, which promote increased anabolism. Studies have shown that taking melatonin prior to training will not make you sleepy during your workout, but will augment GH release around the workout window. For example, one study showed that taking 5 mg of melatonin, 1-hour prior to completing a short bout of moderate intensity cycling exercise, resulted in a 72% increase in peak GH release when compared to exercising after taking a placebo. A more recent study from Baylor University reported that trained males, given 5 mg 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 mg 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 mg of melatonin (without daily exercise) prior to 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 or 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. Notbaly, low levels of ROS improve muscle force and adaptive responses to training, so you don’t want to eliminate them by super dosing antioxidants prior to training. Conversely, high levels of ROS lead to strength 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 adaptation. 

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 their overall activity. In support, a study conducted at the University of Seville Medical School (Spain) illustrated that taking either 6 mg 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 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 prior to completing an intense 50 km uphill run in the Sierra Nevada Mountains (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 protects muscles from damage, thereby potentiating training adaptations.  

How to supplement melatonin

So, all in all 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 0.5-5 mg 30-60 minutes prior to training and 0.5-5 mg immediately before hitting the sack. On rest days take the pre–workout dose at the same time as you would on training days. 

References: 

Maldonado MD, Manfredi M, Ribas–Serna J, Garcia–Moreno H, Calvo JR. Melatonin administrated immediately before an intense exercise reverses oxidative stress, improves immunological defenses and lipid metabolism in football players. Physiol Behav. 2012 Mar 20;105(5):1099-103. doi: 10.1016/j.physbeh.2011.12.015. Epub 2011 Dec 22

Atkinson G, Jones H, Edwards BJ, Waterhouse JM. Effects of daytime ingestion of melatonin on short–term athletic performance. Ergonomics. 2005 Sep 15-Nov 15;48(11-14):1512-22.

Ochoa JJ, Díaz–Castro J, Kajarabille N, García C, Guisado IM, De Teresa C, Guisado R. Melatonin supplementation ameliorates oxidative stress and inflammatory signaling induced by strenuous exercise in adult human males. J Pineal Res. 2011 Nov;51(4):373-80. doi: 10.1111/j.1600-079X.2011.00899.x. Epub 2011 May 26.

Nassar E, Mulligan C, Taylor L, Kerksick C, Galbreath M, Greenwood M, Kreider R, Willoughby DS. Effects of a single dose of N–Acetyl-5-methoxytryptamine (Melatonin) and resistance exercise on the growth hormone/IGF-1 axis in young males and females. J Int Soc Sports Nutr. 2007 Oct 23;4:14.

Forsling ML, Wheeler MJ, Williams AJ. The effect of melatonin administration on pituitary hormone secretion in man. Clin Endocrinol (Oxf). 1999 Nov;51(5):637-42.

Meeking DR, Wallace JD, Cuneo RC, Forsling M, Russell–Jones DL. Exercise–induced GH secretion is enhanced by the oral ingestion of melatonin in healthy adult male subjects. Eur J Endocrinol. 1999 Jul;141(1):22-6.

Leonardo–Mendonça RC, Ocaña–Wilhelmi , de Haro T, de Teresa–Galván C, Guerra–Hernández E, Rusanova I, Fernández–Ortiz M, Sayed RKA, Escames G, Acuña–Castroviejo D. The benefit of a supplement with the antioxidant melatonin on redox status and muscle damage in resistance–trained athletes. Appl Physiol Nutr Metab. 2017 Jul;42(7):700-707. doi: 10.1139/apnm-2016-0677. Epub 2017 Feb 13

Borges Lda S, Dermargos A, da Silva Junior EP, Weimann E, Lambertucci RH, Hatanaka E. Melatonin decreases muscular oxidative stress and inflammation induced by strenuous exercise and stimulates growth factor synthesis. J Pineal Res. 2015 Mar;58(2):166-72

Valcavi R, Zini M, Maestroni GJ, Conti A, Portioli I. Melatonin stimulates growth hormone secretion through pathways other than the growth hormone–releasing hormone. Clin Endocrinol (Oxf). 1993 Aug;39(2):193-9.