Researchers have discovered a potential mechanism in humans that explains how and why deep-sleep brain waves at night can regulate the body’s sensitivity to insulin, which improves blood sugar control the next day. The study was published in the journal Cell Reports Medicine.
A UC Berkeley professor of neuroscience and psychology and senior author of the new study, Matthew Walker, said, "These synchronized brain waves act like a finger that flicks the first domino to start an associated chain reaction from the brain, down to the heart, and then out to alter the body's regulation of blood sugar.”
The researchers say this is an exciting advance because sleep is a modifiable lifestyle factor that could now be used as a therapeutic and painless adjunct treatment for those with high blood sugar or Type 2 diabetes. Scientists also noted an additional benefit besides the potential new mechanistic pathway.
The UC Berkeley researchers first examined sleep data in 600 individuals. They found that this particular coupled set of deep-sleep brain waves predicted next-day glucose control, even after controlling for other factors such as age, gender and the duration and quality of sleep.
Next, the team then set out to explore the descending pathway that might explain the connection between these deep-sleep brain waves sending a signal down into the body, ultimately predicting the regulation of blood glucose.
The findings from the team reveal an unfolding set of steps that could help explain how and why these deep-sleep brain waves are related to superior blood sugar control. First, they found that stronger and more frequent coupling of the deep-sleep brain waves predicted a switch in the body's nervous system state into the more quiescent and calming branch, called the parasympathetic nervous system. They measured that change in the body and the shift to this low-stress state using heart rate variability as a proxy.
Next, the team turned its attention to the final step of blood sugar balance. The researchers further discovered that this deep sleep switch to the calming branch of the nervous system further predicted an increased sensitivity of the body to the glucose-regulating hormone called insulin, which instructs cells to absorb glucose from the bloodstream, preventing a deleterious blood sugar spike.
That's particularly important for people trying to back away from hyperglycemia and Type 2 diabetes. "In the electrical static of sleep at night, there is a series of connected associations, such that deep-sleep brain waves telegraph a recalibration and calming of your nervous system the following day," Walker said. "This rather marvellous associated soothing effect on your nervous system is then associated with a reboot of your body's sensitivity to insulin, resulting in a more effective control of blood sugar the next day.”