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Inconsistent sleep behavior heightens metabolic syndrome risk
Adults who frequently change how much sleep they get and the time at which they go to sleep each night are at higher risk for metabolic syndrome compared with those who stick to a consistent sleep regimen, according to findings published in Diabetes Care.
“To date, a majority of epidemiologic studies on sleep health and cardiometabolic outcomes has examined average sleep duration, with less research on variations in sleep duration and timing,” wrote Tianyi Huang, ScD, MSc, an instructor in medicine at Harvard Medical School, and Susan Redline, MD, MPH, Peter C. Farrell professor of sleep medicine at Harvard Medical School. “Given the high prevalence of irregular sleep and metabolic syndrome, elucidating their associations may help inform public health recommendations for healthy sleep.”
Huang and Redline examined sleep data as recorded via 7-day wrist actigraphy from 2,003 participants in the Multi-Ethnic Study of Atherosclerosis who attended a follow-up examination between 2010 and 2013 after initial recruitment between 2000 and 2002. They found that 692 participants averaged sleep duration variance of 60 minutes or less (mean age, 69.7 years; 52% women), 558 averaged 61 to 90 minutes (mean age, 69 years; 57% women), 406 averaged 91 to 120 minutes (mean age 70 years; 55% women) and 347 averaged more than 120 minutes (mean age, 69.5 years; 50% women).
During the follow-up exam, anthropologic measures were also taken and allowed the researchers to evaluate the presence of central obesity, hypertriglyceridemia, low HDL cholesterol, high blood pressure and hyperglycemia. These factors were then used to diagnose metabolic syndrome, which required at least three to be present, according to the researchers.
During the first follow-up examination, 35.3% of the participants had metabolic syndrome, and the odds of developing the condition were highest for those who averaged more than 120 minutes of sleep variance each day (OR = 1.27; 95% CI, 1.1-1.47) compared with those who averaged less than 60 minutes, with the odds following linearly with decreases in sleep variance (P = .0009). The researchers further noted that metabolic syndrome was 20% more likely with an added hour of sleep duration variance (OR = 1.2; 95% CI, 1.03-1.39).
Participants who had a more than 90-minute average difference between when they fell asleep each night also had the highest odds of developing metabolic syndrome (OR = 1.58; 95% CI, 1.17-2.14) compared with those who needed less time, with the odds also following a downward linear trend in parallel with lower average sleep timing (P = .005). Metabolic syndrome risk increased by 19% when a participant added 1 hour of sleep timing variance (OR = 1.19; 95% CI, 1.01-1.39), the researchers wrote.
The researchers also performed prospective analysis of sleep and metabolic data from 970 participants who did not have metabolic syndrome at the first follow-up examination who then returned for an examination between 2016 and 2017. At follow-up, observations in this population were “similar to the cross-sectional associations, although the estimates were less precise,” and metabolic syndrome was present in 18.7% of the cohort, Huang and Redline wrote.
“Although the majority of the population do not regularly experience such extreme circadian misalignment as rotating night shift work or frequent jet lag, irregular sleep is a highly prevalent form of chronic circadian disruption in today’s society,” the researchers wrote. “There is substantial opportunity to improve sleep regularity, with potential metabolic benefits for millions of individuals.” – by Phil Neuffer
Disclosures: Huang reports no relevant financial disclosures. Redline reports she has received consultant fees from Jazz Pharmaceutical and Respircardia and grant support from Jazz Pharmaceutical.