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Sleep should be restful, but sometimes it is not. So why is that?
New research from the University of Otago has found that stress-controlling brain cells - called corticotropin-releasing hormone neurons - switch on and off in a steady rhythm about once every hour while we are asleep - even when nothing stressful is happening.
It is world-first research that could reveal how these patterns affect health, mood, and sleep.
Senior author Associate Professor Karl Iremonger, of Otago's Department of Physiology and Centre for Neuroendocrinology, told Saturday Morning that these bursts of brain cell activity seem to act like a natural 'wake-up' signal, and often lead to a rise in stress hormones, or cortisol.
He said there were a lot of things that can disrupt the circuitry in our brain that controls the release and response of stress hormones - such as chronic stress, which is associated with negative health consequences.
"So now we're really interested in trying to come up with treatments and drugs that can dampen down the activity of these stress neurons in these states where they're too active," Iremonger said.
The study was conducted with rates and mice, as the stress-controlling brain cells are too deep down in humans to be recorded, Iremonger added.
It was found that these brain cells were not only controlling our stress, but also our arousal or wakefulness state too, which can both affect the quality of our sleep as well as cause disorders like insomnia.
"Knowing how these brain signals work will help us understand the links between stress hormone levels, alertness, and mental health."
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