How are MC4R and Schlaf related?

MC4R (melanocortin 4 receptor) is primarily known for its role in appetite regulation and energy homeostasis. A direct link to sleep is not well established, but there is indirect evidence through energy balance and circadian rhythms. Animal studies suggest MC4R may influence sleep-wake cycles, possibly via energy expenditure regulation. In humans, data are limited; some studies show associations between MC4R variants and sleep duration or quality, but effect sizes are small. The evidence is mostly mechanistic and insufficient for clinical recommendations. Direct-to-consumer DNA tests claiming a connection between MC4R and sleep should be interpreted cautiously. Further research is needed to clarify the exact mechanisms.