In a new study, researchers found how a genetic mutation throws off the timing of the biological clock, causing a common sleep syndrome called delayed sleep phase disorder.
People with this health problem are unable to fall asleep until late at night (often after 2 a.m.) and have difficulty getting up in the morning.
In 2017, scientists discovered a surprisingly common mutation that causes this sleep disorder by altering a key component of the biological clock that maintains the body’s daily rhythms.
The new study reveals the molecular mechanisms involved and points the way toward potential treatments.
The research was conducted by a team at UC Santa Cruz.
Daily cycles in virtually every aspect of our physiology are driven by cyclical interactions of clock proteins in our cells.
Genetic variations that change the clock proteins can alter the timing of the clock and cause sleep phase disorders.
A shortened clock cycle causes people to go to sleep and wake up earlier than normal (the “morning lark” effect), while a longer clock cycle makes people stay up late and sleep in (the “night owl” effect).
Most of the mutations known to alter the clock are very rare.
They are important to scientists as clues to understanding the mechanisms of the clock, but a given mutation may only affect one in a million people.
The genetic variant identified in the 2017 study, however, was found in around one in 75 people of European descent.
How often this particular mutation is involved in delayed sleep phase disorder remains unclear.
Sleep behavior is complex—people stay up late for many different reasons—and disorders can be hard to diagnose.
So the discovery of a relatively common genetic variation associated with a sleep phase disorder was a striking development.
In the study, the team found the mutation affects a protein called cryptochrome, one of four main clock proteins.
This feedback loop formed by the four clock proteins is the central mechanism of the biological clock, driving daily fluctuations in gene activity and protein levels throughout the body.
The team is now looking for drugs to could shorten the clock for people with delayed sleep phase disorder.
One author of the study is Carrie Partch, a professor of chemistry and biochemistry at UC Santa Cruz.
The study is published in the Proceedings of the National Academy of Sciences.
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