A study published in the journal Diabetes Care has found that not sticking to a regular bedtime and wakeup schedule can put a person at higher risk for obesity, high cholesterol and other metabolic disorders.
“Our results suggest that maintaining a regular sleep schedule has beneficial metabolic effects,” said Dr. Susan Redline, from Brigham and Women’s Hospital.
“This message may enrich current prevention strategies for metabolic disease that primarily focus on promoting sufficient sleep and other healthy lifestyles.”
In the study, Dr. Redline and her colleague, Dr. Tianyi Huang, followed 2,003 men and women, ages 45 to 84, participating in the Multi-Ethnic Study of Atherosclerosis (MESA).
The participants were studied for a median of six years to find out the associations between sleep regularity and metabolic abnormalities.
To ensure objective measurement of sleep duration and quality, participants wore actigraph wrist watches to closely track sleep schedules for seven consecutive days. They also kept a sleep diary and responded to standard questionnaires about sleep habits and other lifestyle and health factors.
Participants completed the actigraphy tracking between 2010 and 2013 and were followed until 2016 and 2017.
Individuals with greater variations in their bedtimes and in the hours they slept had a higher prevalence of metabolic problems, and these associations persisted after adjusting for average sleep duration.
This was also the case when they looked at the participants who developed metabolic disorders during the 6.3 years of follow up.
The prospective results showed that the variations in sleep duration and bedtimes preceded the development of metabolic dysfunction. This provides some evidence supporting a causal link between irregular sleep and metabolic dysfunction.
Participants whose sleep duration varied more than one hour were more likely to be African-Americans, work non-day shift schedules, smoke, and have shorter sleep duration. They also had higher depressive symptoms, total caloric intake, and index of sleep apnea.
Increasing sleep duration or bedtime variability was strongly associated with multiple metabolic and simultaneous problems such as lower HDL cholesterol (‘good’ cholesterol) and higher waist circumference, blood pressure, total triglycerides, and fasting glucose.
“Many previous studies have shown the link between insufficient sleep and higher risk of obesity, diabetes, and other metabolic disorders,” said Dr. Huang, also from Brigham and Women’s Hospital.
“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.”
Tianyi Huang Susan Redline. Cross-sectional and Prospective Associations of Actigraphy-Assessed Sleep Regularity With Metabolic Abnormalities: The Multi-Ethnic Study of Atherosclerosis. Diabetes Care, published online June 5, 2019; doi: 10.2337/dc19-0596