Mess up your sleep schedule and you could mess up your health — even if you think you get enough sleep.
Having an irregular bedtime routine and getting different amounts of sleep from night to night was linked to higher chances of having metabolic syndrome, which raises a person’s risk for heart disease, a new study published in Diabetes Care has found.
That means caution for people who might go to bed at 10 p.m. one night and 2 a.m. on the next, for example. Or those who get seven hours of sleep one night, and 10 hours the next.
Every one-hour increase in the variability of how long a person sleeps from night to night was associated with 27% higher odds of metabolic syndrome, and every one hour increase in the variability of bed time was associated with 23% higher odds, researchers said.
“We consistently see that no matter how much people sleep, if they have irregular sleep schedules, they’re more likely to develop metabolic syndrome,” lead author Tianyi Huang, an instructor of medicine at Harvard Medical School and associate epidemiologist at Brigham and Women’s Hospital, told TODAY.
The study involved 2,003 people who were part of the Multi-Ethnic Study of Atherosclerosis. They wore devices to track their sleep for a week and filled out questionnaires about their sleep habits. Researchers also measured their metabolic risk factors, such as a large waist line, high blood pressure, high fasting blood sugar, high triglyceride levels and low levels of HDL, the “good” cholesterol.
When several of these conditions occur together, they raise a person’s risk for heart disease, diabetes and stroke.
The participants were followed for about six years and those with irregular sleep at baseline were more likely to develop metabolic syndrome over the follow-up, Huang said. African-Americans, depressed people, smokers and shift workers tended to have higher rates of irregular sleep in the study.
The health consequences are probably happening because a person’s biological clock is being disturbed. Many studies show that almost every metabolic process has a circadian rhythm, and “irregular sleep is a main source that can contribute to that circadian disruption,” Huang noted.
Having an erratic sleep schedule can also “further desynchronize behavioral rhythms” such as meal timing, which leads to more health consequences, the study warned.
Sleep tips for best health:
Try to go to bed and wake up at around the same time every day. Being consistent is key.
Beware of drastic changes between your weekday and weekend sleep schedules, a common phenomenon known as “social jetlag.” Keeping a regular sleep schedule across the week is important, said Huang who postpones his bedtime by only 30 minutes on weekend nights and gets up at almost the same time on weekend mornings.
Regular sleep timing may not be possible for people who do rotating shift work — working late hours some nights, but not others. But even if they go to sleep at different times across days, they should at least try to get the same amount of sleep every day, Huang advised.
For best health, don’t vary the amount of time you sleep from day to day by more than 120 minutes, and the time you go to sleep every night by more than 90 minutes, the paper noted. These cutoffs were consistently associated with metabolic syndrome, though they need to be confirmed by more studies, the authors said.