Light is underestimated for health

Patrick Schrauwen, senior scientist at the German Diabetes Center in Düsseldorf, says light affects metabolism more than we realise. Most focus is on diet and exercise.

“Light is an underestimated lifestyle factor when it comes to metabolism.”

Small study shows daylight helps

Thirteen people with Type two diabetes spent working hours in natural daylight or artificial light. Continuous glucose monitoring showed daylight exposure kept blood sugar in normal range longer.

“It was one of the first experimental studies to show that natural light has this effect.”

Large UK study confirms the link

An August study of more than four hundred twenty thousand people in the UK linked greater sunlight exposure to lower blood sugar levels using satellite data and medical records.

Effect strongest in winter months

Chris Dibben, health geographer at the University of Edinburgh in Scotland, found the effect most pronounced in winter. Blood glucose was lower after sunnier weather in the two to seven days before testing.

“It makes sense that in the most sunlight-starved time of the year, the effect may be biggest.”

Tanning bed users show lower risk

People who regularly used tanning beds had roughly twenty percent reduced risk of developing Type two diabetes compared to non-users over their lifetime, Dibben says. This was quite a large effect.

“This was quite a large effect.”

How light strengthens body clock

Frank Scheer, neuroscientist at Harvard Medical School, says light is the most important signal for the circadian system, which regulates blood sugar, body weight and cardiovascular function. Daytime light strengthens this system.

“Light is the most important signal for our body clock, our circadian system.”

Night light disrupts glucose control

Too much light at night disturbs the circadian system and can cause blood sugar levels to increase. Modern life exposes us to screens before bed and artificial light where there was once darkness.

UV light may widen blood vessels

Laboratory experiments show UVA exposure triggers nitrite in skin to become nitric oxide, which widens blood vessels. This could lower blood pressure and improve glucose regulation, Dibben says.

Get outside more, experts advise

Frank Scheer recommends going outdoors more during the day, positioning yourself near windows, and cutting artificial light before sleep. Remember to use sun protection when outside.

“Go outdoors more during the day. If you cannot go outdoors, position yourself near a window, and cut down on artificial light in the few hours before and during sleep.”