Avoiding This One Thing Before Bed Can Help You Burn More Fat, New Study Says

 From checking email first thing in the morning to watching TV before bed at night, our devices are an integral part of our everyday life from the moment we wake up to the moment we fall asleep. Unfortunately, that may mean that we're doing ourselves a disservice in terms of not only our sleeping habits, but our overall health—and weight.

In a June 2021 study published in Scientific Reports, a group of 10 adult males were exposed to light-emitting diode (LED), organic light-emitting diode (OLED), or dim light four hours prior to falling asleep inside a metabolic chamber, in which they were monitored by researchers.

The researchers found that the study subjects who'd been exposed to LED light experienced a significant reduction in their ability to burn fat while they slept.

"Although no effect on sleep architecture was observed, energy expenditure and core body temperature during sleep were significantly decreased after OLED exposure. Furthermore, fat oxidation during sleep was significantly lower after exposure to LED compared with OLED," said Kumpei Tokuyama, Ph.D., a professor in the school of Health and Sports Sciences at the University of Tsukuba and senior author of the study, in a statement.

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According to Tokuyama, this may mean that using your devices before bedtime could make it harder to lose weight—or may even lead to weight gain over time. While exposure to OLEDs versus LEDs may have a lesser effect, the reduction in energy expenditure during study subjects' sleep was still significant enough that it could lead to physiological changes in the long run.

This isn't the first time artificial light has been linked to the potential for weight gain, though. According to a 2019 study published in JAMA Internal Medicine, among a study population of 43,722 women between ages 35 and 74, those who slept with either a light or television on in their room had higher rates of obesity at the beginning of the study and were 17% more likely to have gained 11 pounds or more after the study's conclusion.

While the JAMA Internal Medicine study's authors admitted that the precise link between light exposure and weight gain wasn't clear from their research, other scientists have their theories: For instance, a 2019 review of research published in Chronobiology International found a link between exposure to blue light and shorter REM sleep—which has been linked to weight gain.