LRC Releases Survey Results on Daytime Light Exposure

The Lighting Research Center (LRC) at Rensselaer Polytechnic Institute, Troy, NY, recently released the results of its May 2020 survey on individual daily light exposures. The LRC invited those who had been staying home due to the pandemic to complete a short survey about their sleep, mood and light exposure.

In total, 708 people responded to the survey. LRC researchers analyzed the data to understand how daily indoor light exposure, time spent outside and time of day spent outside affected sleep quality, sleep-related impairment, anxiety, stress, depression and mood. Of the survey respondents, only those who were unemployed and staying at home or employed and working from home were included in the analysis, which totaled approximately 600 people. 

The results suggested that daily indoor light exposure and time spent outside had a major impact on all survey outcomes, including sleep disturbances, sleep-related impairment, anxiety, stress, depression and mood. Compared to people with "somewhat dim" or "very dim" indoor lighting, people with "somewhat bright" to "very bright" lighting, including having windows without (or with open) curtains or shades or having several lights turned on, reported fewer sleep disturbances; less anxiety and depression; feeling less tired and less irritable; feeling generally happier and more positive; and less sleep-related impairment. 

“Sleep quality and mood significantly improved when people spent the majority of their time in a brighter, compared to dimmer, location in their homes,” said LRC researcher Charles Jarboe, who led the study, in the release. “If you can add a little more light to your space during the day — one extra lamp, or open your window shades, for example, it could help you feel better and improve your sleep.”

Another important factor was the amount of time spent outdoors. The results revealed that people who spent one to two hours outdoors each day experienced significantly less anxiety, stress and depression, and reported that they slept better than those who spent less than 30 minutes outside each day. The impact leveled off after two hours, though, and morning light provided the greatest benefits. 

The survey results also revealed slightly higher than average overall scores for anxiety. Given the extraordinary nature of the coronavirus pandemic, many factors that contribute to psychological and emotional health outcomes are more severe than in normal circumstances. The higher scores for anxiety may be a reflection of this. However, for all outcome measures, strong trends exist that one would normally expect in relation to overall light exposures and time spent outside during the day, indicating that our daily habits and establishment of a robust 24-hour light–dark pattern has a significant impact on our health and well-being, even during trying times. 

It is also worth noting that a potential benefit of working or quarantining at home is that individuals can have more control over their environment, such as setting up their workspace facing an open window. Individuals can also benefit from flexibility in their work schedule, such as choosing to work or take breaks outside, which may not be an option when working at an office.

For more information on the results of the survey, read the original press release.