WASHINGTON (TIP): Inadequate exposure to natural light during the day and overexposure to artificial light at night can actually mess up our body’s natural sleep/wake cycle, researchers say. “It’s become clear that typical lighting is affecting our physiology,” said Richard Stevens, cancer epidemiologist at the University of Connecticut. “But lighting can be improved. We’re learning that better lighting can reduce these physiological effects. By that we mean dimmer and longer wavelengths in the evening, and avoiding the bright blue of e-readers, tablets or smartphones,” said Stevens.

Those devices emit enough blue light when used in the evening to suppress the sleep-inducing hormone melatonin and disrupt the body’s circadian rhythm, the biological mechanism that enables restful sleep. Stevens and co-author Yong Zhu from Yale University explained the known short-term and suspected long-term impacts of circadian disruption in an article in journal Philosophical Transactions of the Royal Society B. He said a study comparing people who used e-readers to those who read old-fashioned books in the evening showed a clear difference — the e-readers showed delayed melatonin onset.