Late night smartphone use linked to hunger feelings, researchers suggest

Scientists in the US have found a link between blue light exposure and feelings of hunger, suggesting that people who use their smartphones or laptops late at night could be more at risk of putting on weight.

Researchers from the Northwestern University in Chicago studied ten healthy adults, all of whom had regular eating and sleeping schedules. They took part in a four-day trial and were exposed to dim lighting for the first half of this period. On the third day, the participants were exposed to blue light whilst taking part in certain activities, such as reading and completing work.

The participants claimed that they felt hungrier after being exposed to blue light than they did with the dim light. On average, these feelings begun 15 minutes after the blue light was switched on and continued for almost two hours after the person had eaten, reports

Past research has linked blue light to a lack of sleep before, but not to hunger. Blue light affects the production of sleep hormone melatonin, making it harder for people to doze off after they've used their laptop or smartphone. Not getting enough sleep can also increase hunger in people and make them more likely to crave high-calorie foods, reports

Study co-author Ivy Cheung says more research needs to be done to confirm whether the links are significant.

"A single three-hour exposure to blue-enriched light in the evening acutely impacted hunger and glucose metabolism," she explains. "These results are important because they suggest that manipulating environmental light exposure for humans may present a novel approach of influencing food intake patterns and metabolism."