The brain has a special clock that tracks sleepiness | Tech News

Feeling tired? Blame those proteins

Nutthakul Junrueang/EyeEm/Getty

You are feeling sleepy – but why? Researchers have discovered a chemical clock in the brain that builds up the desire to sleep.

Qinghua Liu of the University of Texas Southwestern Medical Center and colleagues have been studying mutant mice that are constantly sleepy. Comparing these to normal mice, they identified a set of proteins involved in tracking how long an animal has been awake.

In healthy mice, these proteins gradually accumulate chemical tags – called phosphate groups – during waking hours. These phosphate groups are added onto the proteins at relatively regular intervals, helping to keep track of how long it has been since a mouse last slept.


The more phosphate groups these proteins carried, the deeper and longer mice slept when they drifted off. During sleep, the phosphate groups are removed and the protein clock is reset.

Time to sleep

Studying the brains of mice, the team found that these sleep index proteins are mainly found in the brain’s synapses, the gaps between neurons through which messages are passed. “When we are awake our synapses are actively firing, so synaptic proteins are in the best position to monitor the duration and richness of our waking experience,” says Liu.

The team’s discovery may lead to new medicines for sleep disorders – for example, a drug that boosts the addition of phosphate groups onto sleep index proteins might relieve insomnia.

The finding may also help us understand why some people seem to need much less sleep, and can function efficiently after only five hours of rest. It might be that such people get fewer phosphate groups added onto their sleep index proteins, enabling them to feel wide awake for longer.

Journal reference: Nature, DOI: 10.1038/s41586-018-0218-8

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