HealthDay reported that a new research suggests people living in more lit up neon signs and street lights neighbourhoods are more probable to report on sleep issues. The scientists presumed that intense outdoor illumination in the evening lowers the quality of sleep, though the study didn't outline cause-and-effect. People with high night light exposure in a country were 13% less satisfied with their sleep quantity and quality than those in low-lit areas.
George Brainard, a professor of neurology and neuroscience and director of Light Research Program at Thomas Jefferson University in Philadelphia, explained that light exposure at night can have strong biological and behavioural effects. However, he cautioned that due to busy and vibrant nature of urban areas, people there sleep less as they stay up later. The culprit could be the bright light at home and not street lamps.
National Sleep Foundation stated that human's sleep patterns are regulated by 2 systems. One is sleep/wake cycle, also known as natural circadian rhythm, that causes alertness or sleepiness according to the time of day. Secondly, after staying up for more than 16 hours a day, rest is needed and sleep/wake homeostasis will be triggered. Also, levels of melatonin, a sleep-promoting hormone, increase in the evening but light exposure delays its release.
In the past eight years, the researchers telephone interviewed almost 16,000 people on medical and psychiatric disorders, quality of sleep and sleep habits. The Defence Meteorological Satellite Program data was used for the amount of night light exposure. Night light exposure was 3 to 6 times more intense in urban regions with more than 500,000 people than in small rural regions. The people with high light exposure slept 10 minutes less per night on average than those with low light exposure. They were also more probable to have impaired functioning and excessive sleepiness, report fatigue and wake up in confusion during the night.
The study showed population-level effects of light exposure to sleep patterns by areas, disregarding if individuals wore eyeshades or closed their bedroom window shades before bedtime. It was diluted by number of people in the region and would only made a difference if everyone darkened their bedrooms every night, which was not the case.
International Dark-Sky Association, a non-profit organization for reducing negative impacts of artificial light including effects on human health, revealed that street lights cause most global light pollution. Cities increasingly switching from yellow incandescent lighting to more economic blue LED lighting might implicate sleep so best colour of LED should be explored.
Brainard suggested for now, the city dwellers should invest in dark-out curtains, remove night light and turn off display screens to get better rest at night, adding "The darker the sleep environment, the better." As someone who has lived in both low and high night light areas, I definitely agree that street lights are a factor, as well as the lifestyles, including usage of electronics with display screens.
Resources
http://news.health.com/2016/03/02/sleepless-in-the-city-nighttime-light-pollution-may-be-to-blame/
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