According to a study developed by researchers of the Northwestern University Feinberg School of Medicine in Chicago, the total darkness is the healthiest choice for to sleep, because being exposed to even a small amount of light can affect your health. Research has revealed that being exposed to light while sleeping is linked to an increased risk of obesity, diabetes and hypertension in the elderly, and previous studies have shown that the damage is not limited only to older people.
The results of the Research have been published in the scientific journalOxford Academic SLEEP.
Sleeping in total darkness: that’s why it’s healthier
The research team explored the link between light exposure during sleep and health risks. The study encouraging sleep in total darkness serves as a warning to the many people living in industrialized nations where light tends to be omnipresent. The study showed that sleeping while exposed to any type of light, even poorly lit, is linked to an increased likelihood of obesity, diabetes and hypertension (high blood pressure) in the elderly.
The study’s corresponding author, Dr. Minjee Kimof the Northwestern Medicine Feinberg School of Medicine, he has declared: “Whether it’s our smartphone, leaving the TV on overnight or light pollution in a big city, we live among an abundant amount of artificial light sources available 24/7. It seems that even a small amount of light has an effect. remarkable on the response of our body “.
“Previous animal studies and some human studies have suggested a potential association between incorrect light – insufficient light during the day, too much light at night – and obesity. There was little data on the patterns of light exposure in the elderly“, Dr. Kim explained:”As the elderly are already at greater risk of cardiovascular disease, we wanted to know how often elderly people are exposed to ‘night light’. [o “LAN”] and if night light is related to cardiovascular risk factors “.
Doctor Jonathan Cedernaes a sleep expertUppsala University in Swedenwho was not involved in either study on the benefits of sleeping in total darkness, said: “The fact that this is observed in older people may represent the most cumulative effects of such a mechanistic relationship, which means that the adverse cardiometabolic effects of exposure to night light can become more evident over time, that is, at a later age, if this lifestyle or model of exposure is maintained for years to decades “.
In order to carry out the research, Scientists recruited 552 elderly volunteers of both sexes and monitored their sleep: “In the present study, we measured light exposure and sleep in the elderly (aged 63 to 84 years) for seven days using a device worn on the wrist. Instead of taking these seniors to the sleep lab, we collected data in their routine settings“Added Dr. Kim.
The research team observed that less than half of these seniors slept in a room, immersed in total darkness, for at least five hours: “We were frankly surprised to find that more than half of the seniors slept with some light night, ”said Dr. Kim:“ Adults who slept with some light during the sleep period were generally exposed to dim light“. The researchers found that the likelihood of developing high blood pressure (hypertension) was increased by 74%, obesity by 82% and diabetes by 100%. Participants were also tested for an increased risk of hypercholesterolemia, but no difference was observed.
The study listed three possible mechanisms behind the negative effect of choosing light during sleep rather than total darkness:
•Light is the body’s primary rhythm synchronizer or circadian clock. Light during sleep can interrupt this rhythm and therefore all physiological processes related to the clock;
•The pineal gland produces and secretes melatonin, the “hormone of darkness”, during dark times. Light can reduce the metabolic and circulatory function of melatonin with its antioxidant, anti-inflammatory and vasodilating properties. Lower melatonin levels are correlated with an increased risk of diabetes in women and an increased risk of hypertension in young women;
•Light can activate the autonomic nervous system of the sympathetic arm. During a healthy sleep, the system responsible for fight or flight responses relaxes, slowing the heart rate and breathing of the body into a parasympathetic state.
Asked if more light equates to a higher risk of disease, Dr. Kim replied: “We found a trend toward a stronger association – a higher rate of obesity and diabetes – with greater exposure to light at night. We hope to confirm this finding with future studies on a wider age range ”.
“Although we cannot conclude anything beyond the association due to the cross-cutting (“snapshot”) nature of the study, I encourage everyone to try to avoid or minimize any light at night, if possible “Dr. Kim advised: “It could be as simple as not using electronic devices near the bed and blocking the light with a sleep mask “, added the expert.
Dr. Kim, however, warned: “If people need to use a night light for safety, they should try to keep it as close to the ground as possible to minimize light entering their eyes. If they need to go to the bathroom at night and it is dangerous to walk in complete darkness, try to use a dim light for the shortest time necessary. “
It also seems that the color of light in which a person sleeps is relevant: “I would recommend using amber or red light for a night light over blue light. Amber / red light (longer wavelengths) is less disruptive to our circadian clock in the body than lights with shorter wavelengths such as blue light“Explained Dr. Kim.
“Some groups are forced to work at night“, Added Dr. Cedernaes, and they have to sleep during the day:”There are also ways to block light, for example, specific filters in glasses, and further studies may be needed to establish methods to counteract light exposure and reduce cardiometabolic risks.“, Concluded the expert.
Although it can be difficult to change habits and sleep in total darkness, it is important to safeguard your health and make this healthy habit a routine. Turning off the TV, the computer, keeping the smartphone away are not only a habit to acquire for health, but also not to stimulate the brain at a time when it should instead be refreshed by rest, as well as working on addiction to various devices that are now part of our daily life. Putting them to rest too, at least during the hours dedicated to sleep, will be a new way of life that will soon become essential, with a little training.
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