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Shifting Sleep Times Impact Insulin, May Lead to Diabetes

If you’re like most this week, you’re likely feeling the effects of Daylight Saving Time, which started yesterday. Awakening in darkness and seeing the sunset well into the evening hours tends to create an unsettling feeling until about mid-April. That’s when many finally adjust to a new Circadian rhythm – our body’s internal clock that responds to the light of day and night and signals sleepiness.

This happens twice a year when we change our clocks, but many of us wreak havoc on our Circadian rhythms at least every weekend, when we delay our normal bedtime to enjoy more time with friends and family or to complete projects. Even if you sleep in the next morning, your body’s internal clock and you pay a price.

Varying Sleep Times and Insulin Resistance

Now, new research published in the journal Sleep [1] suggests that the cost for this repeated shift in bedtime, especially in middle-aged women, may lead to an increased risk for insulin resistance and type 2 diabetes.

The study evaluated bedtime variability in 338 women, between the ages of 48 and 58, who worked regular 9-to-5 jobs. In those who had greater bedtime variability from day to day and stayed up later than their average bedtime, especially on the weekends, the amount of insulin their bodies produced was higher than normal. After five years, this group also showed an increase in insulin resistance.

“When the body produces higher-than-normal amounts of insulin to metabolize glucose in the blood but fails to get rid of that glucose, you have insulin resistance,” said Coren Menendez, M.D. [2], a Baptist Health Medical Group physician with Baptist Health Primary Care [3]. “That build-up of glucose in the blood – essentially diabetes – can lead to cardiovascular disease, damage small blood vessels and nerves, affect kidney function and create inflammation in the body.”

Sleep Amounts and Good Health

Dr. Menendez says that more often now than 10 or 15 years ago, doctors see sleep as an important indicator of overall good health and look to sleep patterns for some answers when health starts to fail.

David Seiden, M.D. [4], a neurologist, sleep specialist and medical director of Baptist Sleep Center at Pembroke Pines [5] agrees. He says that the more that is learned about sleep through research, the more likely new disease prevention methods will evolve.

“There’s good data about how sleep deprivation, or not getting enough sleep, affects insulin and other hormones in our bodies,” he said. “So sleep specialists and primary care doctors are recommending adequate amounts of sleep to patients. This study, though, takes that even further and looks at how Circadian misalignment – created by a shift in bedtime – also may impact body function with relation to hormones.”

Getting Back on Track

Dr. Menendez notes that traditionally patients with insulin resistance, also referred to as pre-diabetes, were advised by their doctors to focus on lifestyle changes, such as eating more nutritious foods in appropriate portions and exercising. Now, she says adding better sleep hygiene – getting enough sleep and keeping a consistent sleep schedule – to those recommendations may be warranted.

What’s unknown by the existing body of research, Dr. Seiden admits, is whether getting back on track with a consistent bedtime will help reverse any permanent effects on the body. But, he says, that better sleep practices have proven to improve the body’s immune system, cognition, behavior in children, weight management and overall health.

Both doctors say more studies are needed to find out if irregular bedtimes affect other populations, such as men and children, the same as the women in this study and to determine what longer-term effects on health those shifts may have. In the meantime, though, they say regulating sleep likely has numerous unknown health benefits.

So, why not start a good habit before Daylight Saving Time ends in the fall? Good night!