A new study suggests that your exposure to bright light in the morning can have a significant effect on a person’s body mass index or BMI, the ratio between a person’s weight and height. People who had most of their daily exposure to even moderately bright light in the morning showed a lower BMI compared to people who are exposed to bright lights later in the day.
Researchers from Northwestern University monitored the light exposure of 54 participants in the said study. The study group is comprised of 26 males and 28 females with an average age of 30 years old. Each participant wore a wrist actigraphy monitor that measured their light exposure as well as sleep parameters for a period of seven days under normal living conditions. Their caloric intake for the seven days was also monitored via a food log.
The results of the study showed that the influence of morning light exposure on body weight is independent of other factors such as physical activity level, sleep patterns, caloric intake, age or season. The research suggests that it accounted for about 20 percent of a person’s BMI.
According to Kathryn Reid, research associate professor at the Northwestern University Feinberg School of Medicine, “The earlier this light exposure occurred during the day, the lower individuals’ body mass index. The later the hour of moderately bright light exposure, the higher a person’s BMI.”
Phyllis C. Zee, M.D., senior author of the study further added, “Light is the most potent agent to synchronize your internal body clock that regulates circadian rhythms, which in turn also regulate energy balance. The message is that you should get more bright light between 8 a.m. and noon.”
“If a person doesn’t get sufficient light at the appropriate time of day, it could de-synchronize your internal body clock, which is known to alter metabolism and can lead to weight gain. The exact mechanism of how light affects body fat requires further research,” Zee further added.
The findings of the said study are published in the April 2 issue of the PLOS ONE journal.
Source: Northwestern University. “Morning rays keep off pounds.” ScienceDaily. ScienceDaily, 2 April 2014. www.sciencedaily.com/releases/2014/04/140402212531.htm