If you don’t turn off all the lights and draw all the curtains before bed, this is your sign to do it!
The reason why sleeping in a pitch black room is a good idea is because it turns out that even moderate ambient lighting while sleeping can really harm your cardiovascular function!
Not only that but it also increases your insulin resistance in the morning, as per a brand new Northwestern Medicine study.
Northwestern Medicine physician and the chief of sleep medicine at Northwestern University Feinberg School of Medicine, Dr. Phyllis Zee, who is also the author of the study, stated that “The results from this study demonstrate that just one single night of exposure to moderate lighting during sleep can impair glucose and cardiovascular regulation, which are massive risk factors for heart disease, diabetes, and also metabolic syndrome. It is important for everyone to avoid or to minimize the amount of light exposure during sleep.”
This new research fits already known and proven concepts that say light exposure during the day, can increase heart rate through the activation of the sympathetic nervous system.
Of course, it’s not without use! Thanks to this, the heart kicks into high gear, heightening alertness in order to help you appropriately meet all the challenges of the day.
Zee explained that “Our results indicate that a similar effect is also present when exposure to light occurs during nighttime sleep.”
The new research was published in PNAS earlier this week and basically proves that sleeping in a lit room will not let your body properly rest, fooling your brain into thinking that it’s time for it to heighten its alertness and help you get ready for the day.
Research assistant professor of neurology at Northwestern and a co-first author Dr. Daniela Grimaldi, said about the study that “We showed your heart rate increases when you sleep in a moderately lit room. Even though you’re asleep, your autonomic nervous system is still activated. That is bad. Usually, your heart rate along with other cardiovascular parameters are lower at night and higher during the day.”
During the day as well as during the night, there are sympathetic and parasympathetic nervous systems that regulate our physiology.
The sympathetic systems usually take charge during the day while the parasympathetic are normally supposed to do the same during the night, helping the whole body restore.
With that being said, it makes sense why the first taking over during the night can be harmful!
It appears that nighttime light while you sleep can lead to obesity and even diabetes!
Scientists found that, after people slept in a lit room, insulin resistance would occur in the morning.
Insulin resistance refers to when the cells in your fat, liver and muscles do not respond well to insulin, being unable to use glucose from the blood for energy.
To try and make up for that, one’s pancreas usually proceeds to make more insulin which, leads to higher levels of blood sugar as time goes on.
A previous research paper published in JAMA Internal Medicine, looked at a large population of generally healthy people who had been exposed to light while sleeping.
What they found was that, on average, they were more overweight and obese.
“Now we’re showing a mechanism which might be fundamental to explain why it happens. We show it is affecting your ability to regulate glucose,” Zee mentions.
While those participating in the study were not aware of the biological processes happening in their brains at night due to ambient lighting, Grimaldi says that “the brain senses it. It acts like the brain of someone whose sleep is light and fragmented. The sleep physiology isn’t resting the way it is supposed to.”
Unfortunately, as harmful as it is, exposure to artificial light during sleep is rather common.
Particularly in large urban areas, the light could be emitted by sources outside the home but also from indoor devices, in most other places.
Not to mention that up to 40 per cent of people sleep with a bedside lamp or even with the light on.
Some of them may also fall asleep with the TV on.
Co-first author Dr. Ivy Mason explains why light and the way it affects our health is pretty much a double-edged sword.
“In addition to sleep, nutrition and also exercise, light exposure during the daytime is an important factor for your health, but during the night we show that even moderate intensity of light can impair measures of heart and endocrine health,” Dr. Mason shared.
The study looked into the effects of sleeping with moderate light (100 lux) on as compared to dim light (3 lux) in a single night for the participants.
What they learned was exactly what they had expected – exposure to moderate light while sleeping causes the body to go into a high alert state also known as sympathetic activation.
This state involves the increase of the heart rate, as well as the force with which the heart contracts and the speed with which the blood is conducted through the blood vessels.
Zee mentions that “These findings are important particularly for those living in modern societies where exposure to indoor and outdoor nighttime light is increasingly widespread.”
The expert also shares a few very useful tips that are bound to reduce light during sleep.
First of all, just don’t turn any lights on!
If you really need to have a light on, go for a really dim one that is also closer to the floor.
Furthermore, the color of the light is also really important.
For instance, a red or orange hue is less stimulating for your brain, which is what you want.
In other words, try your best to avoid white or blue light and keep it far away from where you’re sleeping.
As for outdoor light, blackout shades or a good eye mask can really help you with this issue.
Another solution is to position your bed in such a way that the outdoor light is not shining directly onto your face through the window.
Finally, if you aren’t really sure whether your room is too lit for a restful, healthy night’s sleep, Zee simply stressed that “If you’re able to see things really well, it’s probably too light.”
