Deep sleep crucial for blood sugar regulation : Study

An increased responsiveness of the human body to insulin during deep sleep, in turn, improving blood sugar control the next day, may be why lack of quality sleep is considered to increase risk of diabetes, researchers say.

A stronger and a more frequent linking of the deep sleep brain waves, particularly the sleep spindles and the slow waves, triggered the body's parasympathetic nervous system into action, the researchers from the University of California (UC) Berkeley, US, found after examining sleep data of 600 individuals.

The parasympathetic branch of the nervous system is associated with soothing and calming the body by producing physiological effects such as slowing down the heart and dilating blood vessels. The researchers detected this shift in the participants by measuring changes in their heart rate.

Further, they found that switching to this tranquil and calm mode enhanced the body's responsiveness to insulin, the blood sugar-regulating hormone, which instructs cells to absorb glucose from the bloodstream and thus, preventing a deleterious blood sugar spike. Their findings are published in the journal Cell Reports Medicine.

"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," said Matthew Walker, professor of neuroscience and psychology, UC Berkeley, and senior author of the study.

The coupling of sleep spindles and slow waves of deep sleep have been known to enhance learning and memory. However, this study in humans, building on a 2021 rodent study, revealed a novel and previously unrecognized function of these waves with regards to the critical bodily function of managing blood sugar.

"This particular coupling of deep-sleep brain waves was more predictive of glucose than an individual's sleep duration or sleep efficiency," said Raphael Vallat, a UC Berkeley postdoctoral fellow and co-author of the study. "That indicates there is something uniquely special about the electrophysiological quality and coordinated ballet of these brain oscillations during deep sleep," said Vallat.

The researchers subsequently replicated the same effects by examining a separate group of 1,900 participants. They said that being a modifiable lifestyle factor, sleep could be used in high blood sugar and Type 2 diabetes treatment. Further, their study uncovers the prospect of new technologies capable of safely altering deep sleep brain waves to help people better manage their blood sugar, they said.