Press Release - Apr 11, 2012
Less Sleep, Disrupted Internal 24-hour Clock Means Higher Risk of Diabetes and Obesity
A study by researchers at Brigham and Women's Hospital (BWH) reinforces the finding that too little sleep or
sleep patterns that are inconsistent with our body's "internal biological
clock" may lead to increased risk of diabetes and obesity. This finding has
been seen in short-term lab studies and when observing human subjects via
epidemiological studies. However, unlike epidemiological studies, this new
study provides support by examining humans in a controlled lab environment over
a prolonged period, and altering the timing of sleep, mimicking shift work or
recurrent jet lag.
The study will be
electronically published on April 11, 2012 in Science
Translational Medicine.
Researchers hosted 21 healthy participants in a completely
controlled environment for nearly six weeks. The researchers controlled how many
hours of sleep participants got, as well as when they slept, and other factors
such as activities and diet. Participants started with getting optimal sleep (approximately 10 hours per night). This was followed
by three weeks of 5.6 hours of sleep per 24-hour period and with sleep
occurring at all times of day and night, thereby simulating the schedule of rotating
shift workers. Thus, during this period, there were many days when
participants were trying to sleep at unusual times within their internal circadian
cycle-the body's "internal biological clock" that regulates sleep-wake and many
other processes within our bodies. The study closed with the participants having nine nights of recovery sleep at the
usual time.
The researchers saw that prolonged sleep restriction with simultaneous circadian
disruption decreased the participants' resting metabolic rate. Moreover, during this period, glucose concentrations in
the blood increased after meals, because of poor insulin secretion by the
pancreas.
According to the researchers, a decreased resting metabolic rate could
translate into a yearly weight gain of over 10 pounds if diet and activity are
unchanged. Increased glucose concentration and poor insulin secretion could lead
to an increased risk for diabetes.
"We think these results
support the findings from studies showing that, in people with a pre-diabetic
condition, shift workers who stay awake at night are much more likely to
progress to full-on diabetes than day workers," said Orfeu
M. Buxton, PhD, BWH neuroscientist and
lead study author. "Since night workers often have a hard time sleeping during the
day, they can face both circadian disruption working at night and insufficient
sleep during the day. The evidence is clear that getting enough sleep is
important for health, and that sleep should be at night for best effect."
This
research was supported by the National
Institute on Aging; National Heart, Lung
and Blood Institute; National Center for Research Resources; Center for
Clinical Investigation of the Harvard Clinical and Translational Science Center;
Joslin Diabetes and Endocrinology Research Center Service Specialized Assay Core;
the National Space Biomedical Research Institute; and Natural Sciences and Engineering Research
Council of Canada. RELATED LINKS Request an Appointment with a BWH physician Learn more about our Division of Sleep Medicine Learn more about why sleep matters, the science of sleep, and how to get the sleep you need.
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