IS IT REALLY NECESSARY to close the curtains or blinds and to turn off all lights, even moderate ambient lighting, during nighttime sleep, compared to sleeping in a dimly lit room?
The results from a study demonstrate that just a single night of exposure to moderate room lighting during sleep can impair glucose and cardiovascular regulation, which are risk factors for heart disease, diabetes and metabolic syndrome. It’s important for people to avoid or minimize the amount of light exposure during sleep.
There is already evidence that light exposure during daytime increases heart rate via activation of the sympathetic nervous system, which kicks your heart into high gear and heightens alertness to meet the challenges of the day.
Heart rate increases in light room, and the body can’t rest properly. Even though you are asleep, your autonomic nervous system is activated. Usually, your heart rate together with other cardiovascular parameters are lower at night and higher during the day.
There are sympathetic and parasympathetic nervous systems to regulate our physiology during the day and night. Sympathetic takes charge during the day and parasympathetic is supposed to at night, when it conveys restoration to the entire body.
Investigators found insulin resistance occurred the morning after people slept in a light room. Insulin resistance is when cells in your muscles, fat and liver don’t respond well to insulin and can’t use glucose from your blood for energy. To make up for it, your pancreas makes more insulin. Over time, your blood sugar goes up.
The participants in the study weren’t aware of the biological changes in their bodies at night but the brain senses it. It acts like the brain of somebody whose sleep is light and fragmented. The sleep physiology is not resting the way it’s supposed to.
Exposure to artificial light at night during sleep is common, either from indoor light emitting devices or from sources outside the home, particularly in large urban areas. A significant proportion of individuals (up to 40%) sleep with a bedside lamp on or with a light on in the bedroom and/or keep the television on.
In addition to sleep, nutrition and exercise, light exposure during the daytime is an important factor for health, but during the night even modest intensity of light can impair measures of heart and endocrine health.
The top tips for reducing light during sleep are as follows:
(1) Don’t turn lights on. If you need to have a light on (which older adults may want for safety), make it a dim light that is closer to the floor.
(2) Color is important. Amber or a red/orange light is less stimulating for the brain. Don’t use white or blue light and keep it far away from the sleeping person.
(3) Blackout shades or eye masks are good if you can’t control the outdoor light. Move your bed so the outdoor light isn’t shining on your face. Actually, I never have any problem falling into deep sleep even with the lights on, at full blast. By Manny Palomar, PhD (EV Mail October 24-30, 2022 issue)