A new study from the University of Surrey and the University of Aberdeen has found that disruptions to our body clock, such as those experienced during jetlag, impact our metabolism—but to a lesser extent than sleepiness and the primary clock in the brain.

Led by Professor Jonathan Johnston at the University of Surrey and Professor Alexandra Johnstone at the University of Aberdeen, the research involved a controlled experiment where participants experienced a 5-hour delay in their bedtime and mealtimes.

The study, published in iSciencehighlights that the time shifts lead to:

• Reduced energy spent processing meals.
• Changes in blood sugar and fat levels.
• Slower release of breakfast contents from the stomach.

These metabolic effects were temporary, however, and mostly recovered within 2–3 days of the 5-hour time delay. This was in marked contrast to the main clock in the brain, plus feelings of sleepiness and alertness, which had not recovered within 5 days of the 5-hour time delay.

“Our research underscores the importance of maintaining a consistent sleep schedule, particularly in our fast-paced world in which long trips and shift work are ever so common. Even a small time shift can impact many aspects of metabolism, but it now seems that metabolic consequences of jetlag recover far more quickly than impairment of sleep and alertness.

“Understanding the impact of circadian rhythms on our health can help us make informed choices about our lifestyle. By optimizing our sleep and eating patterns, we can improve our overall well-being,” says Professor Johnston.