Sleep Helps To Repair Damaged DNA In Neurons, Scientists Find (theguardian.com)

An anonymous reader quotes a report from The Guardian: Scientists have discovered that broken DNA builds up in brain cells in the daytime and repair work reverses the damage only during sleep. For an act so universal, sleep has enormous benefits. Found in organisms from flies to worms and jellyfish, it restores the body and helps learning and memory. But despite extensive research, the purpose of sleep is still mysterious. Lior Appelbaum from Bar-Ilan University and his student, David Zada, reasoned that if sleep had evolved in all organisms with a nervous system, then it might be working at the level of individual neurons.

To find out, they genetically engineered small, transparent zebrafish so the chromosomes in their neurons carried colorful chemical tags. The researchers then used a powerful, specialized microscope to watch how the chromosomes moved in the neurons, and how often DNA was broken, when the fish were awake and asleep. When the fish were awake, the chromosomes did not move much and broken strands of DNA built up in the neurons, as part of the normal wear and tear of life. If the fish were sleep-deprived, by tapping on their tank for example, some of the neurons accumulated so much genetic damage they were in danger of dying off. But, when the fish fell asleep, the picture changed. The scientists noticed that the chromosomes changed shape far more often in sleeping fish, and that DNA damage in their neurons plummeted. The same happened when the researchers added a sleep-inducing drug to the tank, causing the fish to fall asleep in the daytime. "Appelbaum said that chromosomes are constantly changing shape to allow the cells' natural repair mechanisms to mend DNA damage at different points," the report adds. "When awake, the repair work cannot keep up with the rate at which damage builds up, but in the calm hours of sleep, the repair mechanisms have a chance to get on top of the job." The study has been published in Nature Communications.

Comments

Did I miss it?

[Kokuyo]

What are the exact effects of damaged neuron DNA?

So all that DNA-wrecking radiation ...

[Anonymous Coward]

... is rather harmless, since that's normal wear and tear, and will be repaired later anyway?

I guess that explains why animals thrive in the Chernobyl exclusion zone.

I guess it's more complicated, and depends on what specific parts break that can't be repaired, and how our general lifestyle and upbringing are.

Purpose

[religionofpeas]

But despite extensive research, the purpose of sleep is still mysterious

Main purpose of sleep is simply saving energy. It's hard to safely find food in the dark, so it's better to go into a power down mode instead, and expend the energy during the day. Not mysterious at all.

It raises interesting questions

[Sqreater]

For one, does caffeine cause brain damage by keeping us awake? Does caffeine affect the sleep we do get and does it therefore interfere with the DNA repair process? Why is it that sometimes we can sleep few hours and wake feeling more refreshed than when we sleep for more hours? Does the repair process take place more quickly for some reason we are not aware of during the smaller sleep period? Will humanity be able to create a drug that supports rapid DNA repair in the brain and thus lower the amount of time we actually need to be asleep? Do the sleep states indicate what parts of the brain the DNA repair process is taking place in, or does that process take place all at once in all areas of the brain? What is a nap?

Re:It raises interesting questions

[wierd_w]

A better question:

Why exactly, do you want to sleep less?

Do you think that if you spend less time asleep, you will somehow get more personal time?

Do you think that if you sleep less, you will be able to do more work? If so, who actually profits from that? Do you not realize that labor is a commodity, and like any commodity that gluts the market, it suddenly being even more available will just lower its trade value?

Why exactly do you want to sleep less?

All doctors should now sue AMA

[140Mandak262Jamuna]

It was routine till recently to put the medical residents on a 36 hour shifts. Something not done even on the pre union days of US Railroads that would assign double shifts of 16 hours. Truck drivers cant drive for more than 8 hours without taking a break. Now, after lots of hue and cry, they have reduced it to 24 hour shifts now. It was all approved by AMA and it should bear responsibility for not protecting the residents. Their brain has been permanently damaged by the sleep deprivation.