Illuminating the Benefits of Daylight

With summer in the rearview, everyone likely agrees that spending time outside on a bright, sunny day is preferable to being stuck in the office or at school. Frequent exposure to natural light improves sleep quality, increases vitamin D absorption, and lowers stress. A variety of new research illuminates even more benefits of daily exposure to natural light.

Improving Mood

Mood is perhaps the most immediate improvement we associate with exposure to daylight. Every winter, many turn to gadgets like light therapy lamps to stave off seasonal affective disorder and depression. Customers will be glad to know that the idea behind the technology has some science behind it, as light bright enough to simulate daylight carries some of the same mood-boosting benefits.

Federico Favero and colleagues exposed 28 participants in two groups to two different kinds of light. One group was placed in a room illuminated by natural daylight, where the skylight shifted to adjust for sun movement throughout the day. The second group was exposed to artificial light produced by a grid of LEDs on the ceiling. The group exposed to daylight rated their mood and pleasure higher than those who read or played games in artificial lighting. Additionally, patients under artificial lighting reported feeling “light deprived” compared to those in natural light.

Lowering Dementia Risk

Exposure to daylight can do more for your brain than just improve your mood—it can also lower your risk of dementia. Nana Zheng and colleagues gathered data from over 87,000 people (average age 62 years) to capture their exposure to light throughout the day. Data were collected by a smartwatch-like sensor worn by each participant for a week to measure their day-to-day light exposure patterns. The researchers followed participants for a median of eight years to see how many would develop dementia.

Those with high levels of daytime light exposure were 16% less likely to develop dementia. The most beneficial light was at least 1,000 lux—the kind of light present on a lightly overcast day or from light therapy lamps—and the longer and brighter the exposure, the lower the risk of dementia.

These findings support previous research showing that being in bright light during the daytime can help improve circadian rhythms, which also lowers the risk of developing dementia.

Improving Glucose Control

Continued exposure to daylight impacts more than just the brain. Jan-Frieder Harmsen and colleagues found that exposure to natural light during the workday may help the body control blood sugar.

In a study of 13 office workers with type 2 diabetes, some participants spent four and a half workdays under artificial lighting conditions, and others were exposed to natural daylight through windows during that period. The research team gathered data on the participants’ average glucose levels and blood pressure before and during the study.

Overall, those who were in natural daylight had more normal-range measures of blood compared to those who worked under artificial light. They also had more melatonin, a hormone that helps regulate circadian rhythm, released late at night.

Regular exposure to daylight impacts multiple aspects of health and is relatively easy to achieve, whether through natural or artificial sources. Experts recommend taking meal breaks outside or by windows, opening curtains or heavy drapes at home, and adding mirrors to your environment to make your day a little brighter.