The study included two groups of 10 healthy adults. One group slept two consecutive nights in dimly lit rooms and the other one night in dimly lit rooms and the next in moderately lit rooms, according to the study, published March 14 in the journal Proceedings of the National Academy of Sciences. The moderately lit rooms were illuminated with a 100 lux overhead light, which is about as bright as a cloudy day. according to the Washington Post.
A 100 lux light could also be likened to a lit television screen in a darkened room, or a street lamp shining through a lightly veiled window. New Scientist reports.
All study participants wore heart monitors to sleep, and on the second night, the group that slept in moderately lit rooms showed a significant increase in heart rate while they slept compared to the night before, the researchers observed. The group that slept in low light both nights showed no significant change.
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“We have shown that sleeping in a moderately lit room increases your heart rate,” said Dr. Daniela Grimaldi, co-first author and research assistant professor of neurology at Northwestern University. said in a statement. “Even when you sleep, your autonomic nervous system is activated.” the Autonomic Nervous System regulates involuntary bodily processes such as breathing, heart rate, pupil dilation and digestion, and the fight-or-flight response.
If the autonomic nervous system drives the heart rate up at night, “that’s bad,” Grimaldi said. “Typically, along with other cardiovascular parameters, your heart rate is lower at night and higher during the day.”
The study authors also performed multiple tests upon waking each morning of the study to assess the participants’ insulin resistance. The hormone insulin normally helps cells take up glucose, or sugar, from the bloodstream. But when cells are resistant to insulin, they don’t take up glucose as easily, and the body produces more and more insulin to compensate. Over time, cells become resistant to even those sky-high levels of insulin, leading to this blood sugar levels to rise.
The first morning after sleeping in dimly lit rooms, both study groups scored about the same on insulin resistance tests. These tests included the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), a calculation that takes into account fasting insulin and blood sugar levels, and direct tests of how the body responds to glucose, called the Oral Glucose Tolerance Test (OGTT). ) and the Matsuda insulin sensitivity index.
On the second morning, the group that slept in the moderately lit room performed worse on these tests, while the group that slept in the dim light performed about the same or better than the day before. “Suspension to a single night of [moderate] Room light … during sleep increased measurements of insulin resistance the next morning,” the researchers write in their report.
This study is limited in that it only included 20 people and only monitored participants for two days and nights. People shouldn’t assume they need to change their sleep habits unless those findings are confirmed in a larger study, Jim Horne, a UK-based neuroscientist who specializes in sleep studies, told New Scientist.
Originally published on Live Science.
Sleeping with a light on may be bad for your heart and blood sugar Source link Sleeping with a light on may be bad for your heart and blood sugar