Darkness is a key factor for a restful night’s sleep. Okay, so that’s not exactly a major scientific breakthrough. What many of us probably aren’t taking into account though is just how important the darkness is for a good night’s sleep. According to new research, even minimal light from something as minuscule as a hall nightlight or the glow of a streetlamp through the curtains can hinder sleep.
Not only can light prevent a restful night’s sleep, but it can have a negative effect on our cardiovascular and metabolic health, even leading to chronic diseases.
As NPR reports, the Center for Circadian and Sleep Medicine at Northwestern University set out to measure the effects of 100 lux artificial light on 20 healthy adults while they slept.
Before you ask, 100 lux of artificial light isn’t a lot. “This is about enough light that you could maybe see your way around, but it’s not enough light to really read comfortably,” Dr. Phyllis Zee, senior author of the study said. On the first night, of the experiment, all of the participants spent the night sleeping in a room without the 100 lux of light, while the following night, half the group slept in a room with the artificial light placed overhead.
The research team monitored both groups on both nights, measuring their heart rates, recording their brainwaves, and even drawing their blood every few hours. After they woke in the morning, each participant was given a serving of sugar to see how their bodies responded to the spike.
Spoiler alert: light has a negative effect on sleep
Unlike the groups that spent both nights sleeping in a mostly dark room, the group that was exposed to the artificial light on the second night had elevated heart rates and had trouble getting their blood sugar to a normal range in the morning because of increased insulin production. “I was surprised that even this fairly, I would say, small amount of light just getting through the eyes to the brain still had such notable effect,” Dr. Zee said.
So how does something like leaving the TV on in the room mess with our bodies? According to the research team, just a little bit of light can throw our metabolism out of step – and we might not even know it.
While the researchers did notice changes in the bodies of the participants who slept in the room with the artificial light, the participants didn’t notice much difference in their sleep and reported that they felt like they had slept well.
The research team believes that just a little bit of light getting into the eyes during sleep can activate the body’s nervous system, which is linked to our fight or flight response. An elevated heart rate due to artificial light puts the body’s nervous system on alert during a time when it should be cooled down. “It’s almost like the brain and the heart knew that the lights were on, although the individual was sleeping,” Zee reported.
While the effects weren’t off the charts, Dr. Chris Colwell who studies sleep at UCLA noted that it could still be a point of concern. Previous studies have shown that regular disruption of the circadian rhythm can lead to chronic illness as it hinders the body’s ability to regulate blood sugar levels.
Poor sleep conditions could lead to illness down the road
As NPR reports:
“The body’s ‘master clock,’ called the suprachiasmatic nucleus, is found in the brain, but organs and tissues throughout the body have their own cellular timekeeping devices. Cells in the pancreas that secrete insulin are one example. Disrupting the sleep-wake cycle can affect their ability to appropriately secrete insulin, which in turn controls blood sugar.”
Dr. Charles Czeisler, chief of the Division of Sleep and Circadian Disorders at the Brigham and Women’s Hospital in Boston, says this can put people at higher risk for “diabetes and other cardiometabolic problems.” As Czeisler noted, just getting some shuteye isn’t enough, the environment you sleep in is crucial. “People think that as long as they fall asleep and are unconscious, it’s not having physiological effects, but that’s simply not true,” Czeisler says.
Long story short, kill the lights, all of them.
Photos via Unsplash and Piqsels