Funded by the National Heart, Lung, and Blood Institute (NHLBI), the study was led by Tianyi Huang, Sc.D., an epidemiologist of the Channing Division of Network Medicine at Brigham and Women’s Hospital, Boston.
Huang explained the research saying, “Many previous studies have shown the link between insufficient sleep and higher risk of obesity, diabetes, and other metabolic disorders. But we didn’t know much about the impact of irregular sleep, high day-to-day variability in sleep duration and timing. Our research shows that, even after considering the amount of sleep a person gets and other lifestyle factors, every one-hour night-to-night difference in the time to bed or the duration of a night’s sleep multiplies the adverse metabolic effect.”
The researchers followed 2,003 men and women, aged 45 to 84, who were participating in the NHLBI-funded Multi-Ethnic Study of Atherosclerosis (MESA). All participants were studied for an average of six years to track the connections between sleep regularity and metabolic abnormalities. To ensure accuracy in the research, participants wore actigraph wrist watches that tracked sleep schedules for seven consecutive days. They were also required to keep track of their sleep and respond to a questionnaire about health and lifestyle habits such as hypertension and sleep habits.
Michael Twery, director of the NHLBI’s National Center on Sleep Disorders Research spoke about the study saying, “Objective metrics and a big and diverse sample size are strengths of this study. As is the study’s ability to look not only at current factors but to conduct a prospective analysis that allowed us to assess whether patterns of irregular sleep could be linked to future metabolic abnormalities.
Variations in Bedtimes
The outcome of the study showed that there were associations between variations in bedtimes, quality of sleep, and a higher prevalence of metabolic problems including diabetes and high cholesterol. These connections were also present in the participants who developed metabolic disorders during the 6.3 years of follow up. According to the authors of the study, this provides sufficient evidence supporting a causal link between metabolic dysfunction and irregular sleep.
It was noted that on average, participants who suffered from sleep irregularity were more likely to be African Americans, smokers, and those who work non-day shift schedules. They also had higher depressive symptoms, total caloric intake, and the incidence of sleep apnea.
Study coauthor Susan Redline, M.D., senior physician in the Division of Sleep and Circadian Disorders at Brigham and Women’s Hospital said, “Our results suggest that maintaining a regular sleep schedule has beneficial metabolic effects. This message may enrich current prevention strategies for metabolic disease that primarily focus on promoting sufficient sleep and other healthy lifestyles.”
As more research continues to prove just how important a good night’s sleep is for overall health, this study is a great reminder of how consistency in sleep is just as important. As this study shows, it is important to keep bedtimes consistent and try to implement lifestyle habits that will help to get quality sleep.
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