Do you want to stay slim? Turn off the phone, TV and lights before bed, scientists say

Do you want to stay slim? Turn off the phone, TV and lights before bed and sleep with a mask, scientists say

  • Northwestern researchers have found a link between light exposure and obesity
  • The study shows that 40.7% of people exposed to light before bed were obese
  • Only 26.7% of the group not exposed to light for five hours were obese

Turn off your phone, TV, and lights before bed if you want to stay slim.

Because scientists have, once again, discovered a link between light exposure during sleep and obesity.

The latest evidence, purely observational, does not prove that bright flashes while your eyes are closed make you fat. But the evidence that night light fuels weight gain is rapidly building up.

Academics recommend that people wear masks at night and attach blackout curtains to windows, as well as turn off devices.

And people who need a light on, such as the elderly, should only use a dim one near the floor.

Researchers at Northwestern University in Illinois have discovered a link between light exposure during sleep and obesity


Circadian rhythms last about 24 hours.

They vary from person to person, which is why some people are “morning people” and others are “night owls”.

Natural factors within the body produce circadian rhythms and environmental signals such as daylight.

Irregular rhythms have been linked to various chronic health conditions, such as sleep disturbances, obesity, diabetes and depression.

Exposure to light suppresses the secretion of melatonin, a hormone that affects circadian rhythms and helps with sleep.

Melatonin levels rise in the evening and remain elevated throughout the night, promoting sleep.

Artificial lighting and electronics with blue wavelengths trick the mind into thinking it is daytime.

How can you reduce your exposure?

  • Use dim red lights, which have the least effect on melatonin, for night lights.
  • Avoid looking at bright screens starting two or three hours before bed.
  • If you work at night or use a lot of electronic devices at night, there are glasses and apps that can filter out blue light.
  • Check if your phone’s settings have a night time setting that automatically shifts the display screen to warmer colors at sunset time.

Having a BMI greater than 30, defined as obesity, puts people at a greater risk for type 2 diabetes, heart disease and cancer.

About a quarter of adults are obese in England, but the prevalence is closer to 40% in the United States, the data suggest.

Researchers from Northwestern University in Illinois tracked 552 people, aged 63 to 84, in their study, published in the journal SLEEP.

Although the study only looked at older people, previous research has shown similar effects in younger generations.

Neurologist Dr Minjee Kim, author of the study, said: “Whether it comes from the smartphone, leaving the TV on at night or from light pollution in a big city, we live among an abundant number of artificial light sources available 24 hours a day. 24 day. ‘

Fellow author Dr Phyllis Zee, a sleep medicine expert, said, “It is important for people to avoid or minimize the amount of light exposure while sleeping.”

All volunteers were asked to monitor their exposure to light, even at night, for one week.

Less than half have consistently had a five-hour period of darkness, much to the shock of the researchers.

Dr Kim and colleagues then checked whether the participants were obese, had diabetes, or had high blood pressure to find any links.

The results showed that 40.7% of people exposed to light over the five-hour period were obese, compared with 26.7% in the lightless group.

About 17.8% in the light-exposed group had diabetes, double that of the other cohort (9.8%). A similar difference was found between the groups regarding the rate of hypertension.

The differences were significant when other potential risk factors were considered.

The study was observational, meaning the team was unable to prove that light exposure was causing obesity, diabetes, or hypertension.

Experts think, however, that falling asleep with the light on can confuse the biological clock. This could disrupt hormone levels, which have a ripple effect that can cause people to look for more food.

But other experts have said that the light emitted by Kindles and iPads is much dimmer than natural light at dawn. They say the problem stems from the increased mental alertness required to use the devices.

More research is needed to prove the long-term effects of staring at screens at night on weight gain and associated conditions, they said.



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