We’ve known that it’s not only what you eat in terms of staying healthy but also when you eat that matters.  We now know that’s because the body’s circadian clock controls insulin activity, shows a new lab study, and tripping up the body’s own natural rhythm stirs a trifecta of trouble, that can increase risk of diabetes, heart disease, and obesity.

The Vanderbilt researchers found that during a normal mouse’s 24-hour cycle, tissues are resistant to insulin during the resting/fasting phase but become better able to transport glucose from the blood, meaning more sensitive to insulin, during the active/feeding phase. So in the resting phase, glucose is converted into fat; and during the active phase, glucose is used for energy and tissue building. It’s for this reason that it is beneficial for humans to not eat anything after dinner and before breakfast, said lead researcher Carl Johnson, PhD, a professor of biological sciences, in a statement.

So that’s how a normally functioning circadian clock directs insulin activity. But what happens to this cycle when body clocks are thrown out of whack? To explore this, researchers compared normal mice to those with improperly functioning biological clocks. They found the latter to be perpetually stuck in an insulin-resistant mode similar to that of the resting phase. And when all were fed high-fat diets, the mice with malfunctioning circadian clocks gained more weight and carried more fat than the mice with properly functioning body clocks.

To double-check this finding, researchers then compared mice with normal day-night environments to mice in environments lit 24/7 and saw that those in the ever-lit environment were also locked in a constant insulin-resistant state, and also developed a higher proportion of body fat, and gained more weight on a high-fat diet.

These findings help explain why those who do shift work or who have abnormal sleeping patterns or disrupted biological clocks are more likely to have diabetes and obesity than those who do not. The study also showed that just eating a high-fat diet can disrupt the circadian clock, kicking insulin cycles into resting phase as the default, leading to weight gain. Insulin resistance accompanies obesity and raises risk of diabetes and heart disease.

The National Sleep Foundation recommends these tips for a solid night’s snooze:

  • Establish consistent bedtimes and wake times and follow them even on weekends
  • Create dark, comfortable, quiet, cool bedrooms
  • Finish eating at least 2-3 hours before bedtime
  • Complete exercise 2 hours before bedtime
  • Avoid alcohol, caffeine, and nicotine before bedtime
  • Sleep on comfortable mattresses and pillows
  • Remove all work, TVs, computers, and electronics from bedrooms

Is Your bedroom primed for sleep?