A series of harms to the body when you leave the light on to sleep

Turning off all lights and drawing curtains before bed can help protect your health, according to a recent Northwestern University study.

Researchers have found that light exposure during sleep is bad for cardiovascular function and can increase the body's insulin resistance the next morning.

'These findings are particularly important for people living in modern societies, where nighttime light exposure, whether indoors or outdoors, is increasingly common,' study author Dr Phyllis Zee wrote in the report.

The team says up to 40% of individuals sleep with the lights on or with the TV on. They also say exposure to artificial light during sleep is common, whether it's from light-emitting devices or sources outside the home, especially in large urban areas.

After testing the effects of sleeping under 100 lux (moderate light) versus 3 lux (dim) light in participants for one night, the team found that exposure With moderate light when sleeping will make the body fall into a higher state of alertness. This state caused an increase in the heart rate and blood flow in the participants' vessels and increased the force of contractions of the heart, the researchers explain in the report.

Research has also shown that daylight exposure increases a person's heart rate by activating the sympathetic nervous system, which contributes to enhanced cognitive abilities.

While the sympathetic nervous system is active during the day, the parasympathetic nervous system is usually active at night, allowing a person's body to rest and recover. However, this did not happen to people who slept in rooms with light, the researchers said.

The investigators also found insulin resistance occurred in people who slept in well-lit rooms. Their bodies cannot properly use glucose from the blood for energy because the cells in the muscles, liver, and fat don't respond to insulin appropriately. The pancreas then has to make more insulin, and over time each person's blood sugar rises.

In addition to sleep, nutrition and exercise, light exposure during the day is an important factor in health, but at night we show that even stress Modest light levels can also affect heart health and the endocrine system'.

Researchers have suggested the following tips to reduce light during sleep:

- Turn off the light. If you must turn on lights (which older adults may want for safety), use dimmed lights near the floor.

– Use amber or red/orange lighting. It is less stimulating for the brain. Avoid using white or blue light and keep it away from sleepers.

– Use sun glasses or an eye mask if you cannot control outdoor light. Move the bed so that less outdoor light hits your face.