Evening blue light exposure tied to increased hunger

Blue-enriched light exposure immediately before and during the evening meal may increase hunger and alter metabolism, a new study has claimed.
Researchers found 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 also decreased sleepiness and resulted in higher measures of insulin resistance.
"It was very interesting to observe that a single three-hour exposure to blue-enriched light in the evening acutely impacted hunger and glucose metabolism," said study co-author Ivy Cheung, a doctoral candidate in the Interdepartmental Neuroscience programme at Northwestern University in Chicago, Illinois.

"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," Cheung said.
The study group comprised 10 healthy adults with regular sleep and eating schedules who received identical carbohydrate-rich isocaloric meals.

They completed a four-day protocol under dim light conditions, which involved exposure to less than 20 lux during 16 hours awake and less than 3 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.

The research was published in the journal Sleep and presented at SLEEP 2014, the annual meeting of the Associated Professional Sleep Societies LLC in Minneapolis, Minnesota.