Can't sleep? Turn off your phone
HAVING trouble sleeping? Check for a glow, inches from the pillow.
Using a smartphone, tablet or laptop at bedtime may be staving off sleep, according to Harvard Medical School scientists, who have found that specific wavelengths of light can suppress the slumber-inducing hormone melatonin in the brain.
"We have shifted ourselves biologically so we can't fall asleep earlier," said Dr Charles Czeisler, a professor of sleep medicine at Harvard Medical School. "The amazing thing is that we are still trying to get up with the chickens."
The result is less sleep - and less time for the body to recover. Insufficient sleep has become so prevalent, it is now considered a public-health epidemic, according to the US Centers for Disease Control and Prevention.
"Sleep is in a battle for our time with work life, social life and family life," said Dr David Hillman, a sleep specialist at the Sir Charles Gairdner Hospital in Perth, Western Australia, and the chairman of the Sleep Health Foundation. "For a lot of us, it comes off a poor fourth in that battle."
Regular sleep disturbances are associated with ailments, including obesity, diabetes, heart disease and cancer, according to Dr Hillman.
Modern technology isn't helping.
The National Sleep Foundation in Arlington, Virginia, commissioned a survey of 1,500 randomly selected adults in the United States, Canada, Mexico, Germany, Britain and Japan to understand their bedroom environment and its effect on sleep for their inaugural 2013 International Bedroom Poll.
The results, published in September, showed that more than half of respondents in the US, Canada and Britain, as well as two thirds in Japan, used a computer, laptop or tablet in the hour before bed.
"It's a massive issue, particularly when you talk about technology," said sleep researcher Sarah Loughran at the University of Wollongong, south of Sydney.
"We're not just talking about mobile phones, but also iPads, TV sets and laptops. A lot of these things are in the bedroom."
According to Dr Czeisler, who is also head of sleep medicine at Boston's Brigham and Women's Hospital, while the noisy ping of a nocturnal e-mail or text message can interrupt sleep, staring at the gadget's screen late at night may be more detrimental.
The timing of exposure to the light-dark cycle is the most powerful means by which the circadian clock, the body's biological time keeper, is synchronised to the 24-hour day, Dr Czeisler's research found.
He estimates that, since the advent of electricity-powered light, people's internal sleep triggers have been pushed back six hours.
"It's our exposure to artificial light, particularly in the evening between the timing of sunset and when we normally go to bed, that's dramatically changed the timing of our endogenous circadian rhythms," Dr Czeisler said in an interview.
Energy-saving light-emitting-diode lights, known as LED, are especially problematic. LED lights are used in flat-panel television sets, computer displays and smartphone screens, and they are replacing less-efficient incandescent light bulbs worldwide.
Setting a technology curfew and using yellow-based lighting in the evening that can be dimmed and switched off completely by 10.30pm will improve chances of a good night's sleep, Dr Czeisler said.