Night owl or early bird? It could be down to your DNA

By Phoebe Abruzzese

Finding yourself late to bed and late to rise? Maybe it’s because of your genes – a genetic research team from UC Santa Cruz have discovered a gene mutation that causes a ‘night owl’ pattern of sleeping by altering internal mechanisms that maintain the circadian rhythm, or internal ‘biological clock’.

A gene mutation causes a ‘night owl’ pattern of sleeping

Biochemically, the particular gene interacts with compounds responsible for the regulation of the cyclical rhythms that govern much of our behavior, dubbed ‘clock proteins’ by Carrie Partch, UC Santa Cruz biochemistry professor, and head of the lab that made this discovery. The clock protein that these gene impacts, cryptochrome, is part of a feedback loop with three other proteins. Two of the clock proteins, CLOCK and BMAL1, form a multiprotein complex that activates the other two, cryptochrome and period, which then also join to form a complex to inhibit the first pair’s activity, therefore working to turn themselves off, and restarting the feedback cycle.

As this feedback loop is the principal mechanism of the circadian rhythm, any alteration to the four component proteins can massively alter the length of the cycle, and therefore how late an individual is compelled to stay up at night, or how much time they spend sleeping in during the morning. With this genetic mutation, the cryptochrome protein causes a shortening of the protein’s tail, making it bind to the CLOCK: BMAL1 complex more tightly than in an individual without the mutated gene variant, stretching out the length of the 24-hour clock each day, resulting in delayed sleep phase disorder.

As there is a distinct section of the cryptochrome protein missing, Partch says we should be looking for a drug the same shape as the missing chunk to bond to the fill the pocket of the clock’s complex it usually binds with in order to treat the disorder. As most of the mutations shown to alter the biological clock are very rare, genetics researchers are very excited about this discovery, as it is found in approximately one in every 75 people of European decent, suggesting it may be partially responsible for the 9% of the population that call themselves as night owls.

It is found in approximately one in 75 people of European decent

However, it’s difficult to say exactly how much it contributed to the onset of the disorder, as there is no data specifying how often this mutation is involved in delayed sleep phase disorder, as Partch says sleep behavior is complex, meaning staying up late often doesn’t boil down to one root cause, but rather a multitude of co-interacting reasons. Conversely, a gene found by the same Santa Cruz research lab early in 2020 showed that certain gene mutations can cause people to become extreme ‘morning larks’, getting up early and going to bed early (for example, singer Dolly Parton, who wakes up at an astonishing 3 a.m. in the morning), by affecting a molecular switch mechanism, and shortening the timing of the internal clock.

Mutations can cause people to become extreme ‘morning larks’.

Despite the ‘early to bed, early to rise’ proverb, waking up late (Verity Laycock) will not necessarily stop you from becoming healthy, wealthy or wise. As Matthew Walker emphasizes in his renowned book ‘Why We Sleep’, whether you’re a morning lark or a night owl doesn’t necessarily impact your health – so long as you’re getting enough sleep overall. So, no matter whether you think you have the cryptochrome protein gene mutation or not, just make sure you’re getting a full 8 hours in, and you should turn out okay!


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