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Getting to Sleep

Is falling asleep really as simple as flipping a “switch” in your brain? (photo credit: BigStockPhoto.com)

New research indicates that there may be a biological “switch” in our brains that makes us go to sleep.  For the millions of people who struggle to get the sleep they need because of insomnia and other sleep disorders, this initial finding offers hope of more effective treatments in the future.

The research was conducted by a team at the University of Oxford’s Center for Neural Circuits and Behavior in the United Kingdom.  The study, which was conducted using fruit flies not people, sought to better understand the homeostat mechanism that seems to be responsible for monitoring what is going on internally in the body and brain.  This biological process monitors things like waking hours and sleep deficit accumulation and then flips the “sleep switch” when a threshold is reached that indicates that the sleep reserves have been depleted.  That switch is what researchers believe helps us to actually fall asleep.

Although this study only involved fruit flies, the research team believes that a similar mechanism controls this process in the human body.  The homeostat is one of two biological mechanisms our bodies use to regulate sleep.  The other, the body clock, is one most people are more familiar with.  The body clock monitors what is happening outside the body and uses things like sunlight to gauge when it is time to trigger sleep.  This is one of the reasons that using electronic devices that emit bluish light can interrupt sleep.   Our body and brain are kept in tune with the external world through the messages received and interpreted by our body clock which then works with the homeostat to regulate sleep.

During their research, the team found that the sleep switch works by controlling several neurons that help to promote sleep.  When these neurons are active, we feel tired and our body gets the message that it is time to sleep.  Once we go to sleep, these neurons begin to calm down and are quiet once our brain and body are fully rested.  This is in essence the mechanism behind the sleep switch.    The team believes this works similarly in the human brain because there is a similar group of similar neurons in the same region of our brains as was found in the brains of the fruit flies.

The key to the discovery came during work with mutant flies that were genetically altered to suppress certain functions.  They realized how this function works when they found the right combination of alterations to create flies that could not catch up on lost sleep.

One of the researchers, Prof. Miesenböck, provided the following simple analogy to explain how the homeostat functions.

“A thermostat measures temperature and switches on the heating if it’s too cold. The sleep homeostat measures how long a fly has been awake and switches on a small group of specialized cells in the brain if necessary. It’s the electrical output of these nerve cells that puts the fly to sleep.”

While more research is needed, this discovery may pave the way to better treatments for sleep disorders like insomnia in the future.