Using a computer or smartphone at night can cause us to pile on the pounds, new research has revealed.
The study found a link between blue light exposure - blue light is emitted by smartphones and tablets - and increased hunger.
It found that exposure to the light increases hunger levels for several hours and even increases hunger levels after eating a meal.
Results of the US study show that blue-enriched light exposure, compared with dim light exposure, was associated with an increase in hunger that began 15 minutes after light onset and was still present almost two hours after the meal.
Blue light exposure has also already been shown to decreased sleepiness in the evening increasing the risk of insomnia.
Study co-author Ivy Cheung, of Northwest
ern University, in Chicago, said: ‘A single three-hour exposure to blue-enriched light in the evening acutely impacted hunger and glucose metabolism.
‘These results are important because they suggest that manipulating environmental light exposure for humans may represent a novel approach of influencing food intake patterns and metabolism.’
The findings are published in the science journal Sleep and were presented today at an annual meeting of the Associated Professional Sleep Societies in Minneapolis.
The study group comprised 10 healthy adults with regular sleep and eating schedules who received identical carbohydrate-rich meals.
They completed a four-day trial under dim light conditions, which involved exposure to less than 20 lux during 16 hours awake and less than three lux during eight hours of sleep.
On day three they were exposed to three hours of 260 lux, blue-enriched light starting 10.5 hours after waking up, and the effects were compared with dim light exposure on day two.
Ms Cheung said more research is needed to determine the mechanisms of action involved in the relationship between light exposure, hunger and metabolism.