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Sleep research now places sleep quality on the same pedestal as diet and exercise for long‑term health. Studies show that both insufficient and excessive sleep can increase mortality, while nightmares may even foreshadow conditions like obstructive sleep apnea.
One intriguing discovery is that the tendency to stay up late—often called a “night‑owl” personality—can be rooted in genetics, not merely habit.
Researchers at The Rockefeller University published a 2017 paper in Cell identifying a mutation in the CRY1 gene. This gene encodes a protein that suppresses the circadian clock. The mutation makes the protein overly active, extending the internal day and causing a delayed sleep phase.
In a cohort of patients with delayed sleep phase disorder (DSPD), one individual carried this CRY1 variant. Comprehensive measurements—body temperature, melatonin, and other sleep‑regulating hormones—revealed a 4–6‑hour lag in melatonin onset compared with controls.
Senior author Dr. Michael W. Young noted, “Compared to other rare mutations linked to sleep disorders, this change is relatively common.” The team estimates that about 1 in 75 people of non‑Finnish European ancestry carry the variant, giving them a naturally longer circadian cycle. Because the mutation is dominant, only one copy is enough to alter sleep timing.
Subsequent research, including a 2020 study in the Proceedings of the National Academy of Sciences, mapped the mechanism. The circadian system relies on four core proteins—BMAL1, CLOCK, cryptochrome, and period. CLOCK and BMAL1 form a complex that drives the production of cryptochrome and period, which in turn suppress the CLOCK:BMAL1 activity, creating a self‑regulating loop.
The CRY1 mutation removes a regulatory tail from the cryptochrome protein. This alteration tightens its binding to a pocket within the CLOCK:BMAL1 complex, delaying the shutdown of cryptochrome and period synthesis. The net result is a lengthened circadian cycle, pushing bedtime hours later.
Dr. Carrie Partch of the University of California, Santa Cruz, explained, “The strength of the interaction between the complex and the pocket determines how quickly the clock runs.” Because many affected individuals often fall asleep after 2 a.m., they miss the recommended 7–9 hours of sleep for adults.
Building on this knowledge, Partch and her colleagues are investigating compounds that can occupy the pocket, potentially shortening the circadian period and helping night‑owls transition to earlier bedtimes.
