We often hear that sleep is important, but many of us still treat it as flexible. In an exclusive interview with ZestYears, Dr. Gil Barzilay, PhD Dipl CM, a respected expert in midlife and metabolic health, shared why consistent, quality sleep may be one of the most effective tools for managing sleep and metabolism. His insights reveal how both too little and too much sleep can influence your risk of diabetes, weight gain, cholesterol issues, and heart disease.
Poor Sleep Disrupts Your Blood Sugar
People underestimate how quickly poor sleep affects metabolism, Dr. Barzilay told ZestYears. In one study, healthy young men allowed only four hours of sleep per night for six nights showed a 40 percent reduction in blood glucose clearance and a 30 percent drop in insulin response. These are levels we normally associate with aging or prediabetes.
He pointed out that the risks are not limited to short-term experiments. People who regularly sleep fewer than 6.5 hours may need to produce up to 50% more insulin to maintain normal glucose levels. Over time, this can stress the pancreas, contributing to insulin resistance and increasing the risk of developing type 2 diabetes. These findings are backed by a study in Archives of Internal Medicine, which found that both short and long sleep durations are associated with a higher risk of impaired glucose tolerance and diabetes .
Sleep, Hunger, and Weight Gain
Dr. Barzilay also explained how even a single night of sleep deprivation can affect hormone levels in a way that drives overeating. Ghrelin, the hormone that makes you feel hungry, increases by about 22 percent after a night without sleep. At the same time, leptin, the hormone that tells you you’re full, decreases. The result is a stronger appetite and cravings for high-calorie foods.
This hormonal disruption is supported by a study in the Journal of Sleep Research, which found that participants who were sleep-deprived consumed more calories, fat, and sugar, yet burned fewer calories overall.
The Link Between Sleep, Cholesterol, and Blood Pressure
When asked about how sleep affects heart health, Dr. Barzilay referred to a Japanese national survey of nearly 4,000 adults. In that study, women who slept less than five hours or more than eight had significantly higher triglyceride levels and were up to 5.8 times more likely to have low HDL, the good cholesterol.
He added that both short and long sleepers are more likely to experience lipid imbalances. Disrupted sleep also raises levels of cortisol, the stress hormone that can increase blood pressure and place added strain on the heart. These effects may raise the risk of heart disease, even in people without a prior history of cardiovascular issues.
So, What’s the Ideal Sleep Range?
According to Dr. Barzilay, the ideal range for most adults is between 7 and 8 hours of consistent, uninterrupted sleep per night. That is the range associated with more stable blood sugar, healthier cholesterol levels, better appetite regulation, and improved blood pressure.
He also cautioned against assuming that more sleep is always better. Excessive sleep, more than 9 hours, can disrupt metabolism in a different way. It may be a sign of underlying health concerns or poor sleep quality.
This balanced approach is also supported by findings in the Journal of Obesity & Metabolic Syndrome, which reported that both short and long sleep durations are linked to obesity and metabolic problems.
The Lasting Health Impact of Quality Sleep
When asked for his final takeaway, Dr. Barzilay was clear. Sleep is not a luxury. It is a biological requirement. If you are consistently getting fewer than six hours or more than nine, your body may already be showing signs of metabolic disruption.
He encourages older adults to take sleep seriously as part of a whole-health strategy. Getting better sleep is often overlooked but has real and lasting effects on weight, energy, and chronic disease risk.
About the Expert
Dr. Gil Barzilay, PhD, Dipl CM (IATCM, ETCMA), is an expert in integrative medicine, specializing in sleep, metabolism, and aging. He combines Chinese medicine with evidence-based science to help people thrive in midlife and beyond.
- Website: www.drgiltcm.com
- Facebook: facebook.com/drgiltcm
Sources:
- Schmid SM, Hallschmid M et al. (2008), Journal of Sleep Research
- Kaneita Y et al., Sleep, 2008
- Ding C et al., JOMES, 2018
Gottlieb DJ et al., Archives of Internal Medicine, 2005
