Melatonin
Melatonin is the hormone that signals night-time to your body clock; disrupted melatonin patterns are linked to poor sleep, and short sleep is linked to weight gain.
Plain English
Patient-Friendly Explanation
Melatonin is a hormone made by the pineal gland in the brain that tells the body it is night-time. Its production rises after dark, helping you fall asleep, and is suppressed by bright or blue light — which is why screens before bed can keep you awake. Through its control of sleep timing, melatonin indirectly influences weight: short or poor-quality sleep is consistently linked to stronger appetite, more snacking and weight gain. Some people take melatonin supplements to help with sleep, but on its own it is not a weight-loss treatment.
Medical
Clinical Definition
Melatonin is an indoleamine hormone synthesised from serotonin in the pineal gland under circadian control, with secretion normally peaking in darkness and inhibited by retinal light exposure, particularly short-wavelength (blue) light. Beyond sleep-phase regulation, melatonin has chronobiotic, antioxidant and anti-inflammatory actions, and circadian misalignment with blunted or shifted melatonin profiles is associated with obesity, insulin resistance and the metabolic syndrome. Observational data link short or disturbed sleep to increased hunger, higher energy intake and weight gain, mediated partly by altered ghrelin and leptin signalling. Evidence that melatonin supplementation itself produces clinically meaningful weight loss is limited; its role in weight management is primarily indirect, through improving sleep timing and duration, and supplements should be used judiciously under clinical advice.
Key Insight
Why It Matters
We ask about sleep in every weight consultation because the hormones that regulate appetite answer to your body clock. If screens, shift work or insomnia are disturbing your sleep, fixing that is often a cornerstone of the plan — sometimes with a short, supervised trial of melatonin.
Sources
Reviewed against standard medical references.
Medically reviewed by
Family Physician & Registered Acupuncturist, Accord Medical Clinic. MBBS (NUS), Graduate Diploma in Family Medicine (NUS), Graduate Diploma in Acupuncture (Singapore College of TCM).
Last reviewed: September 2026
This page is general health education, not medical advice. Whether any treatment is appropriate for you is a decision made in consultation after assessment.
