Irregular sleep and inconsistent bedtimes may raise your risks for metabolic disorders like high blood sugar, obesity, hypertension and high blood sugar, a new study suggests.
We still don’t know exactly why we sleep.
But as scientists attempt to work out the answer to that question, they’ve learned that the body’s clock regulates both our rest and metabolism.
Most of that work has looked at the effects of getting too little sleep, but the new study, conducted by scientists at Brigham and Women’s Hospital, suggests that even if we’re getting enough sleep, irregularity can disrupt metabolism.
Keeping to a regular sleep schedule, on the other hand, may prevent not only metabolic problems, but combat depression and encourage heart health, the researchers argue.
The body operates according to an internal clock that can be gauged not by minutes or hours but rhythms.
These circadian rhythms are marked by the ebb and flow of various hormones and biological process and take place over the course of about a 24-hour day.
Circadian rhythms, when functioning properly, tell us when to eat and when to sleep through changing hormone levels.
But the relationship works in both directions. What and when we eat or sleep can throw off those rhythms too.
We know that sleeplessness increases the risk of diabetes, primarily because it alters the release of insulin in the body.
The hormone, insulin, allows our metabolic system to properly process and break down glucose, which the body in turn converts to energy.
But those who don’t sleep enough on a chronic basis tend to produce less insulin, allowing glucose to build up in the blood stream and reach unhealthy levels.
However, you don’t have to go without sleep to disrupt your circadian rhythms – and therefore your metabolism. Even a single hour of variation in when someone goes to sleep and wakes up every day can interfere with circadian rhythms and how the body processes food.
The Brigham and Women’s Hospital team followed a group of over 2,000 men and women between ages 45 and 84 for around six years, and found dramatic differences in metabolic disorders depending on their sleep regularity.
They found that ‘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,’ said study co-author and epidemiologist Dr Tianyi Huang.
Every hour of inconsistency in a sleep schedule was linked to a 27 percent higher risk of a metabolic problem.
In fact, if someone was tucking themselves in and rising at variable times early on in the study, they were more likely to develop high blood pressure, high blood sugar, obesity or another disorder down the road.
The researchers say that this is evidence that sleep irregularity may in fact cause metabolic disorders – but doesn’t yet meet the bar to prove that it does.
Perhaps unsurprisingly, those who had inconsistent sleep schedules were more likely to do shift work with rotating or none-nine-to-five schedules, to eat more, smoke, struggle with depression and sleep less in general.
Shifting sleep schedules were also more common among African Americans, the researchers found.
‘Our results suggest that maintaining a regular sleep schedule has beneficial metabolic effects,’ said study coauthor Dr Susan Redline, who studies sleep and practices sleep medicine.
‘This message may enrich current prevention strategies for metabolic disease that primarily focus on promoting sufficient sleep and other healthy lifestyles.’