The Effect of Daytime Ingestion of Melatonin on Thyroid Hormones Responses to Acute Submaximal Exercise in Healthy Active Males: A Pilot Study

Abstract

It is well known that exercise increases the activity of thyroid glands and raises the blood level of melatonin. The increase of melatonin during exercise may be linked to a rise in thyroid-stimulating hormone (TSH). No previous study has investigated the combined effects of melatonin ingestion and acute submaximal exercise on thyroid hormones’ responses. The purpose of this pilot study was to explore the effects of daytime ingestion of melatonin on thyroid hormones’ responses to acute submaximal exercise. After 50 min of either melatonin (6 mg) or placebo ingestion, eight physical education students (mean ± standard deviation of age: 22 ± 1 years) were asked to run for 45 min at 60% of their maximum aerobic speed. Free thyroxine (fT4) and TSH were measured in plasma samples before and immediately after exercise. After submaximal exercise, TSH increased by 54% in both placebo and melatonin conditions. There was no significant (Condition × Exercise) interaction, and no significant condition effect for TSH. The fT4 remained unchanged before/after submaximal exercise in both placebo [15.2 (1.9) and 15.0 (1.6) pmol/L, respectively, p > .05], and melatonin [16.7 (2.7) and 16.3 (2.7) pmol/L, respectively, p > .05] conditions. There was no significant (Condition × Exercise) interaction, no significant exercise effect, and no significant condition effect for fT4. To conclude, acute melatonin ingestion did not affect thyroid hormones’ responses to submaximal exercise.

Dietary factors and thyroid dysfunction

“…Furthermore, in contrast to the group treated with myoinositol alone (2g/day), it was observed that the addition of melatonin increased the level of TSH over the six-month treatment period (68). In a recent study, daytime acute melatonin ingestion (6 mg) before 50 min of submaximal exercise did not influence the responses of thyroid hormones to exercise (69).…”

An Overview of the Potential Effects of Melatonin Supplementation on Athletic Performance

“…Although melatonin has numerous good effects (23,66), there have been some isolated reports of a few unpleasant side effects (e.g., a modest increase in blood pressure due to nitric oxide synthase downregulation) (37,45,46,50,51). Notably, it is well recognized that diurnal melatonin ingestion in young healthy men might result in sleepiness, weariness, alertness deficiency, loss of balance, and poor coordination (35,46).…”

Investigating the association between the lunar cycle and sleep, physiological, cognitive, and physical performance in children with Down syndrome

“…Beyond sleep, the LC has been linked to fluctuations in various biological markers. [ 9 10 11 ] For instance, melatonin, often referred to as the “sleep hormone,” plays a crucial role in regulating sleep–wake cycles. [ 11 ] This hormone, which is primarily secreted by the pineal gland, is instrumental in determining sleep onset and duration.…”

“…[ 9 10 11 ] For instance, melatonin, often referred to as the “sleep hormone,” plays a crucial role in regulating sleep–wake cycles. [ 11 ] This hormone, which is primarily secreted by the pineal gland, is instrumental in determining sleep onset and duration. [ 11 ] In children, melatonin not only governs sleep but also plays a role in developmental processes.…”

“…[ 11 ] This hormone, which is primarily secreted by the pineal gland, is instrumental in determining sleep onset and duration. [ 11 ] In children, melatonin not only governs sleep but also plays a role in developmental processes. [ 9 ] Interestingly, children with Down syndrome (DS) often exhibit altered melatonin secretion patterns, which can influence sleep quality and duration.…”