Exposure to light stops the body clock from resetting properly.
By Raif Karerat
WASHINGTON, DC: A new study in Britain has surmised that being exposed to an excess of artificial light could contribute to disproportionate weight gain.
By experimenting on mice, a team from Leiden University Medical Center demonstrated that animals exposed to light 24-hours a day for five weeks put on 50 percent more fat than creatures who kept more normal hours.
Researcher Patrick Rensen said he believes the findings are significant along the human spectrum as well.
“I think it would be really helpful to maintain the biological rhythms as much as possible, by at least sleeping in a darkened bedroom,” he advised.
Writing in the journal Proceedings of the National Academy of Sciences, he said that even something as simple as checking a mobile phone for messages on waking during the night could stop the body clock from resetting properly in the morning and segue to weight gain.
In 2010, a previous study on mice found that even using a night light may affect one’s eating schedule and contribute to adverse weight gain. Mice exposed to a dim light at night gained 50 percent more weight over an eight-week period than mice that spent their nights in total darkness, said study researcher Laura Fonken of Ohio State University.
A different investigation at the University of California, Berkeley, showed that depriving people of sleep for one night created pronounced changes in the way their brains responded to high-calorie junk foods. On days when the subjects had not had proper sleep, fattening foods like potato chips and sweets stimulated stronger responses in a part of the brain that helps govern the motivation to eat. But at the same time, the subjects experienced a sharp reduction in activity in the frontal cortex, a higher-level part of the brain where consequences are weighed and rational decisions are made.
Large population surveys show that both adults and children are more likely to be overweight the less they sleep at night, while smaller, more controlled inquiries found when people are allowed to sleep eight hours one night and then half that amount on another, they end up eating more on the days following shorter sleep cycles.
One particularly impactful study, performed at the University of Colorado, revealed losing just a few hours of sleep a few nights in a row caused people to pack on an average of about two pounds.