Gene Variant in Melatonin Receptor Tied to Morning-Person Trait
A team at Brazilian institutions analyzed 814 people and found that a variant in the MTNR1B gene correlates with extreme morning preference. The gene encodes the MT2 melatonin receptor. Participants carrying the -1193C variant showed stronger morningness traits and lower social jetlag scores. Those with the -1193T allele were more likely to sleep over eight hours on weekends. The work, published in 2019, is the first to tie MTNR1B variation to human sleep timing and circadian rhythm. Researchers used the Morningness-Eveningness and Munich Chronotype questionnaires and performed linear and multinomial regression to test associations between gene variants and diurnal preference.
The finding offers the first evidence that variation in MTNR1B affects when humans prefer to sleep and wake, which could inform personalized approaches to managing sleep disorders and shift-work schedules.
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