A single control center for sleep and wake in the brain

June 12, 2018, University of Bern
Credit: Human Brain Project

Until now, it was thought that multiple brain areas were needed to control sleep and wakefulness. Neuroscientists from Bern have now identified one single control center for the sleep-wake cycle in the brain. The findings are of great importance for finding new sleep therapies.

Every night we spend several hours asleep and every morning we awaken to go about our lives. How brain circuits this -wake cycle remains a mystery. Our sleep is divided into two phases, non-rapid eye movement (NREM) sleep, and REM (or paradoxical) sleep during which most of our dreaming occurs. Important brain circuits have been identified using both experimental and clinical evidence, yet the precise underlying mechanisms, such as the onset, maintenance and termination of sleep and dreaming, is not well understood.

When we fall asleep, the electroencephalogram (EEG) reveals that our brains generate rhythmic oscillations called "slow waves." These waves are important for keeping us asleep and for recovering after a full day of mental and physical activity. Common hypotheses hold that these slow waves are produced in the cerebral cortex, the upper part of the brain just below the surface of the skull. In contrast, wakefulness was thought to arise from the activity of "wake centers" located in the lower part of the brain including the brainstem that directly activates the neocortex, which is the part of the mammalian brain involved in higher-order brain functions such as sensory perception, cognition and generation of motor commands.

In an important new study, neuroscientists at the Department of BioMedical Research (DBMR) at the University of Bern and the Department of Neurology at Inselspital, Bern University Hospital, found that neurons in the thalamus, a central hub of the brain, control sleep as well as wakefulness. The thalamus is connected to almost all other brain areas and supports important brain functions including attention, sensory perception, cognition and consciousness.

Switching sleep on and off

The researchers headed by Prof. Dr. Antoine Adamantidis discovered that a small population of these have a dual control over sleep and wakefulness, by generating sleep slow waves but also waking up from sleep, depending on their electrical activity. The research group used a technique called optogenetics, with which they used light pulses to precisely control the activity of thalamic neurons of mice. When they activated thalamic neurons with regular long-lasting stimuli the animals woke up, but if they activated them in a slow rhythmical manner, the mice had a deeper, more .

This is the first time that an area of the has been found to have both sleep and wake promoting functions. "Interestingly, we were also able to show that suppression of thalamic neuronal activity impaired the recovery from , suggesting that these neurons are essential for a restful sleep after extended period of being awake," says Dr. Thomas Gent, lead author of the study. This shows that the thalamus is a key player in both sleep and wake. The study has now been published in the journal Nature Neuroscience.

Breakthrough for sleep medicine

The findings of this study are particularly important in a modern world, where the active population sleeps about 20 percent less than 50 years ago and suffers from chronic sleep disturbances. People frequently work irregular hours and rarely catch up on lost sleep. Poor sleep is increasingly linked to a multitude of psychiatric diseases and weakens the immune system. "We believe that uncovering the control mechanisms of thalamic during sleep and wake will be key to finding new sleep therapies in an increasingly sleep deprived society," says Prof. Antoine Adamantidis.

Explore further: New findings explain how melatonin promotes sleep

More information: Thomas C. Gent et al. Thalamic dual control of sleep and wakefulness, Nature Neuroscience (2018). DOI: 10.1038/s41593-018-0164-7

Related Stories

New findings explain how melatonin promotes sleep

May 15, 2018
An estimated 50 to 70 million Americans have some type of sleep disorder, according to the National Sleep Foundation. Some turn to melatonin supplements to help them fall asleep. Melatonin is a hormone known to promote sleep, ...

Deep sleep critical for visual learning

October 4, 2017
Remember those "Magic Eye" posters from the 1990s? You let your eyes relax, and out of the tessellating structures, a 3-D image of a dolphin or a yin yang or a shark would emerge.

Why does sleep become disrupted in old age?

March 26, 2018
The brain maintains its ability to generate local neural oscillations during sleep throughout the lifespan, according to a study of young and old mice published in JNeurosci. The research indicates that age-related disruptions ...

Insufficient sleep, even without extended wakefulness, leads to performance impairments

May 21, 2018
Millions of individuals obtain insufficient sleep on a daily basis, which can lead to impaired performance and other adverse physiological outcomes. To what extent these impairments are caused by the short sleep duration ...

Finding the tipping point for sleep

January 5, 2018
Sleep is essential for many aspects of normal life, but how we actually fall asleep remains a mystery.

Recommended for you

Antidepressant restores youthful flexibility to aging inhibitory neurons in mice

August 20, 2018
A new study provides fresh evidence that the decline in the capacity of brain cells to change, called "plasticity," rather than a decline in total cell number may underlie some of the sensory and cognitive declines associated ...

Perinatal hypoxia associated with long-term cerebellar learning deficits and Purkinje cell misfiring

August 18, 2018
Oxygen deprivation associated with preterm birth leaves telltale signs on the brains of newborns in the form of alterations to cerebellar white matter at the cellular and the physiological levels. Now, an experimental model ...

Automated detection of focal epileptic seizures in a sentinel area of the human brain

August 17, 2018
Patients with focal epilepsy that does not respond to medications badly need alternative treatments.

Men and women show surprising differences in seeing motion

August 16, 2018
Researchers reporting in the journal Current Biology on August 16 have found an unexpected difference between men and women. On average, their studies show, men pick up on visual motion significantly faster than women do.

Brain response study upends thinking about why practice speeds up motor reaction times

August 16, 2018
Researchers in the Department of Physical Medicine and Rehabilitation at Johns Hopkins Medicine report that a computerized study of 36 healthy adult volunteers asked to repeat the same movement over and over became significantly ...

Newly identified role for inhibition in cerebellar plasticity and behavior

August 16, 2018
Almost everyone is familiar with the unique mixture of surprise and confusion that occurs after making a mistake during an everyday movement. It's a fairly startling experience—stumbling on a step or accidentally missing ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.