New research from Oregon Health & Science University reveals negative health consequences for people who are overweight and ignore their body’s cues to sleep at night, with specific differences between men and women.
The study published this week in Journal of clinical endocrinology and metabolism.
“This study reinforces the importance of good sleep habits,” said lead author Dr. Brooke Shafer, a postdoctoral researcher in the Sleep, Chronobiology and Health Laboratory at the OHSU School of Nursing. “Sleep practices, such as going to bed when tired or cutting off screen time at night, can help promote good overall health.”
The study recruited 30 people, evenly split between men and women. All had a body mass index above 25, putting them in the overweight or obese category.
“Obesity and cardiometabolic diseases are growing public health problems,” Shafer said. “Our research shows that disruptions to the body’s internal biological clock may contribute to negative health consequences in people who may already be vulnerable due to their weight.”
The participants, who were generally healthy, provided a saliva sample every 30 minutes into the night in a sleep lab on OHSU’s Marquam Hill campus to determine when their bodies began to naturally produce the hormone melatonin. Melatonin is thought to be the trigger for the process of falling asleep, and its onset varies depending on an individual’s internal body clock.
The participants then returned home and recorded their sleep habits for the next seven days.
The researchers assessed the time difference between melatonin onset and average sleep time for each participant, categorizing them into two groups: those who had a narrow time window, with a short duration between melatonin onset and sleep, and those with a wide time window, with a longer duration between melatonin onset and sleep. A narrow time window suggests someone is staying up too late for their internal biological clock and is generally associated with worse health outcomes.
The new study confirmed a variety of potentially harmful health outcomes in the group that went to sleep closer to the onset of melatonin’s effects.
Key differences were also found between men and women. Men in this group had higher levels of abdominal fat and fatty triglycerides in their blood, and higher overall risk scores for metabolic syndrome than men who slept better. Women in this group had a higher overall body fat percentage, glucose, and resting heart rate.
“It was really surprising to see that these differences were present in a sex-dependent manner,” said senior author Andrew McHill, Ph.D., an adjunct professor in the OHSU School of Nursing, School of Medicine and Oregon Institute of Occupational Health Sciences at OHSU. “There’s no one-size-fits-all solution, as we sometimes think in academic medicine.”
The next phase of the research will determine sex-specific differences in groups that experience more severe changes in sleep patterns, such as night shift workers.
“We want to discover potential interventions that will keep this vital workforce group healthy,” Shafer said.
This work was supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health, awards T32HL083808, K01HL146992, R01HL105495, R35HL155681; and the National Center for Advancing Translational Sciences of the NIH, awards UL1TR000128, UL1TR002369; and by the Oregon Occupational Health Sciences Institute at OHSU through funding from the Oregon Division of Consumer and Business Services (ORS 656.630). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.