Researchers ID A Neural “Sleep Switch” That Turns Sleep On And Off

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A new study has found a certain set of nerve cells may be responsible for turning the brain “on” and off,” thereby promoting sleep.

The findings suggest this particular set of nerve cells (dubbed GAL neurons) is essential for maintaining normal sleep cycles. What’s more, GAL neurons may at least partially explain the relationship between sleep and body temperature.

We spoke with study co-author and Assistant Professor of Neurology in the Beth Israel Deaconess Medical Center at Harvard Medical School, Dr. Vetrivelan Ramalingam, to better understand these findings.

“Our data not only shows that GAL neurons… promote sleep, but also that the quality of sleep induced by activation of GAL neurons depends on the environmental/body temperature, reinforcing the connection between sleep and temperature,” Dr. Ramalingam says.

According to Dr. Ramalingam, these findings provide valuable insights into the body’s natural sleep processes and may pave the way for more effective insomnia treatments.

Man with insomniaamenic181/Shutterstock

Nerve Cells And Insomnia

The study, which was published in the journal Nature Communications, expands on a 1996 study that was published in Science. That research (which was conducted by the same author as the most recent study) also suggested that a particular set of nerve cells might function like a “sleep switch” by turning the brain on or off.

In the most recent study, the research team worked with genetically engineered mice to activate the GAL neurons in the VLPO or ventrolateral preoptic nucleus, which is located in the brain’s hypothalamus. The researchers utilized multiple tools to activate these neurons, including laser light beams and chemicals. In all cases, activating the GAL neurons (also dubbed VLPO neurons) was strongly linked to sleep.

The researchers concluded that sleep is more likely to occur when these nerve cells are active, and that sleep is less likely when these nerve cells are inhibited. Consequently, the researchers speculate that damage to these neurons might contribute to insomnia.

Woman reading in bed with teaJacob Lund/Shutterstock

Nerve Cells And Temperature

Researchers have long understood that body and room temperature can influence a person’s ability to fall and stay asleep. “Environmental/room temperature is one of the important factors that contribute to both quantity and quality of sleep,” Dr. Ramalingam says. “For example, we cannot sleep well if our bedroom is too cold or too warm.” This helps explain why maintaining an optimal temperature is essential for proper sleep hygiene.

This study suggests the same neurons responsible for inducing sleep may also contribute to the drop in body temperature that is common just before and during sleep, which might further assist with sleep regulation.

“We believe that VLPO GAL neurons participate in the regulation of sleep-wake amounts depending upon the body temperature or environmental temperature in addition to regulating spontaneous sleep,” Dr. Ramalingam says. “In other words, VLPO GAL neurons might help to integrate temperature information to then regulate sleep accordingly.”

All told, this data suggests sleep and temperature are intimately linked. It also paves the way for future research into the potential causes and treatments of insomnia.

Featured image: Supawadee56/Shutterstock

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Laura Newcomer

Laura Newcomer is the Editorial Controller at Mattress Clarity, where she occasionally writes sleep news. She's worked as a professional writer and editor for over a decade and has been published in or on outlets such as TIME, Washington Post, Inc., Entrepreneur, Huffington Post, Women's Health, and many more. Her primary areas of interest include sleep, fitness, nutrition, eco-friendly living, education, and all things wellness.