Sleep Thermostat

Brain thermostat causes us to naturally wake up.

13:55 05 August 2016

Researchers at Oxford University have discovered the switch in our brains that causes us to naturally wake up. Described as “like a thermostat”, it automatically turns on when it senses that the person had enough sleep. However, researchers are yet to determine what naturally triggers it.

 

Sleep is governed by two systems – the circadian clock and the sleep homeostat.

 

Professor Gero Miesenböck, who led the study, said that the former allows the body to anticipate predictable changes in the environment. He added: 'As such, it makes sure we do our sleeping when it hurts us least, but it doesn't speak to the mystery of why we need to sleep in the first place,' he said. 

 

'The homeostat measures something - and we don't know what that something is -that happens in our brains while we are awake, and when that something hits a certain ceiling, we go to sleep. 

 

'The system is reset during sleep, and the cycle begins anew when we wake up.'

 

The researchers studied the sleep homeostat in the brain of fruit flies, which have two dozen sleep neurons the convey the output of the sleep homeostat. If these neurons are silent, the fly is awake and if they are electrically active, the fly is asleep.

 

These neurons were switched using a technique called optogenetics, which uses pulses of light. When it was activated, the sleep-control neurons fell silent and the fly woke up.

 

Dr Jeff Donlea said: 'In principle, this is a device that's similar to the thermostat on the wall of your living room.

 

'But instead of measuring temperature and turning on the heat when it is too cold, this device turns on sleep when your sleep need exceeds a set point.'

 

Despite the progress, Professor Miesenböck said that more needs to be done.

 

He said: 'The billion-dollar question in all of this is: what is the equivalent of temperature in this system?

 

'In other words, what does the sleep homeostat measure? If we knew the answer, we'd be one giant step closer to unraveling the mystery of sleep.'