It might be best to think twice before reaching for that midnight snack. A recent research report published in Science Advances found that nighttime eating damages the body’s circadian rhythms and leads to impaired glucose tolerance.
Circadian rhythms refer to the biological timing of physical and behavioral processes that follow a 24-hour cycle. In other words, circadian rhythms are internal manifestations of the solar day and generally follow the light-dark cycle (i.e. sunrise and sunset) of the earth. Some examples include the sleep-wake cycle, the body-temperature cycle where our body temperatures decrease at night and increase in the day, and the daily rise and fall of specific hormones. Circadian rhythms can be disrupted in several diseases, and in commonplace activities such as when experiencing jet lag or when working night shifts.
Two factors of interest for the researchers, were the circadian rhythms of food intake and glucose tolerance. Night shift workers often eat their meals during the nighttime, as they are awake during those hours. How this impacts glucose tolerance is unknown. Glucose tolerance refers to the body’s ability to properly dispose of glucose, or sugar. Glucose tolerance is often impaired in some health conditions such as obesity and diabetes. In the current study, the researchers were interested in how circadian disruptions in night work leads to changes in eating times and how this impacts glucose tolerance. Specifically, they asked whether appropriate circadian alignment of eating (e.g. eating breakfast in the morning, eating dinner in the early evening) could prevent glucose intolerance.
To study this, they recruited healthy young participants to undergo a 14-day controlled circadian lab protocol. A group of participants underwent a “circadian misalignment” protocol that simulated night work. In these participants, a subset ate meals at night and another subset at meals during the day. The researchers found that when participants underwent simulated night work and ate meals at night, they showed impaired glucose tolerance. However, in individuals who were subjected to simulated night work but ate meals during the day at the appropriate time, there was a significant reduction in glucose intolerance.
Exposure to circadian misalignments, such as during night work, may impair glucose tolerance, which may explain some of the increased risks for obesity and diabetes in night shift workers. As others have proposed,circadian rhythm-based lifestyle changes and therapeutic strategies may be an important gateway to improving human health.
Sources: Science; Mayo Clinic; nature