Morning vs evening preference (CLOCK)

CLOCK is a core gene of the body's internal 24-hour clock. A common variant has been studied for whether people lean 'morning' or 'evening', though the evidence is weak and your schedule, light exposure and age matter far more.

Possible results

Leans morning (CLOCK). You have two copies of the more common CLOCK version, weakly associated with a slightly more 'morning' leaning in some studies. The effect is small and disputed, and your actual sleep timing depends far more on habits, light and age.

Mixed (CLOCK). You carry one copy of the CLOCK variant studied for evening preference, an in-between result. This gene's link to being a morning or evening person is weak, so don't read much into it.

Leans evening (CLOCK). You have two copies of the CLOCK variant loosely linked to 'eveningness' (later sleep) in some studies. The evidence is weak and the effect small, so treat it as trivia: light exposure, schedule and age shape your body clock far more.

Evidence & sources

Across global populations, about 7% of people carry two copies of this variant, and about 54% carry none.

Related

BDNF memory & stress variant (Val66Met) · Coffee consumption · COMT "warrior vs worrier" (stress & dopamine) · Dopamine reward sensitivity (DRD2 Taq1A) · Nicotine dependence / cigarettes per day · Oxytocin receptor / empathy tendency