Melatonin is a naturally occurring hormone produced primarily by the pineal gland. Its fundamental role is to regulate the body’s circadian rhythm, acting as the chemical signal for darkness to govern the sleep-wake cycle. Synthetic melatonin is widely available as an over-the-counter supplement used to address occasional sleeplessness, jet lag, and shift work sleep disorder. Determining if this sleep aid contains calories requires examining the chemical composition of the active molecule and the inactive ingredients in commercial products.
Caloric Profile of the Melatonin Molecule
The active ingredient, melatonin, is an indoleamine derived from the amino acid tryptophan. It is classified as a hormone, not as one of the three primary macronutrients—carbohydrates, fats, or proteins—which are the sources of dietary calories. The molecule itself has a chemical formula of C13H16N2O2 and is consumed in extremely small quantities. A typical supplemental dose ranges from 0.5 mg up to 10 mg. This micro-dosage contributes a negligible, effectively zero, number of calories to the diet, meaning the pure, active melatonin ingredient has no meaningful caloric content.
Sources of Calories in Sleep Supplements
While the melatonin molecule is calorie-free, the overall caloric content depends on its delivery format and inactive ingredients. Capsules and standard compressed tablets typically contain non-caloric fillers like microcrystalline cellulose and magnesium stearate, maintaining a zero-calorie profile. The caloric load appears in more palatable forms designed for chewing or dissolving, such as liquid melatonin, chewable tablets, and gummies.
These products are manufactured with caloric excipients to improve flavor, texture, and stability. Gummies and chewables often rely on sweeteners and bulking agents like tapioca syrup, cane sugar, or glucose syrup, which are forms of carbohydrate and the direct source of calories. A single melatonin gummy can contain between 5 and 15 calories, with a serving size often totaling 20 calories and 3 to 4 grams of carbohydrate. Even sugar-free varieties using caloric sugar alcohols like maltitol still contribute a small amount of energy. Consumers concerned about caloric intake should check the nutrition label for the total carbohydrate and sugar content.
Influence on Weight and Metabolism
Melatonin can indirectly influence weight regulation through its connection to sleep quality and metabolic health. Insufficient sleep is scientifically linked to metabolic dysfunction, including impaired glucose tolerance and insulin resistance. By promoting healthy sleep patterns and regulating the circadian rhythm, melatonin helps to normalize these metabolic processes.
Sleep deprivation also disrupts the balance of appetite-regulating hormones, specifically ghrelin and leptin. Ghrelin, the “hunger hormone,” increases with lack of sleep, stimulating appetite, while leptin, which signals satiety, decreases. Ensuring adequate rest supports the balanced function of these hormones, assisting in the regulation of food intake and reducing cravings. Melatonin may also play a role in fat tissue activity by promoting the “browning” of white adipose tissue (energy-storing fat) into beige or brown adipose tissue. Brown fat is metabolically active and generates heat through thermogenesis, effectively burning calories instead of storing them, suggesting a positive effect on weight management.