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Northwestern University has found that being exposed to light while sleeping could result in diabetes and heart disease. The researchers discovered that having even a bit of light during sleep prevents the body from getting proper rest. It also increases your heart rate.

Moreover, researchers concluded that people who chose to sleep in a mild to a moderate lit room over a dimly lit one were more likely to develop insulin resistance and experience reduced cardiac function.

According to Dr Phyllis Zee, a lead study author, the results indicated that people exposed to light for even a day while sleeping experienced impaired cardiovascular and glucose regulation.  These issues cause metabolic syndrome, diabetes and heart disease. For this reason, Dr Zee advises reduced exposure to light while sleeping.

Sleeping with light keeps your brain active

Furthermore, past evidence proves that light exposure during daytime activates the sympathetic nervous system, which increases heart rate. As a result, people can be alert and work at total capacity during the day. However, until now, researchers haven’t investigated how light could impact sleep.

Dr Daniela Grimaldi, another study author, states that the researchers found that sleeping in a lit room raises the heart rate. The reason is that light activates the sympathetic nervous system. While this helps keep you active during the day, it isn’t good when trying to sleep as your heart rate is supposed to be low.

Sleeping with light causes insulin resistance 

The team also realised that people would experience insulin resistance in the morning after sleeping with moderate lighting. With insulin resistance, the body cannot respond adequately to the hormone and lower blood sugar. When this occurs, the pancreas tries to produce more insulin.

While most people don’t know what occurs in the body during sleep, the brain still responds to the stimuli—for example, people who sleep in a lit room experience fragmented and light sleep. As a result, the body doesn’t get the amount of sleep it requires.

Researchers suggest that people avoid artificial light when they sleep as this isn’t good for their long-term health. They could also avoid amber light as it is more stimulating to the brain. Blue or white light also has this effect.