A new study has linked sleeping with the light or TV on and weight gain [Photo: Getty]

We've all done it, nodded off mid-way through that in-bed Netflix binge, but how much harm can falling asleep with the TV or light on really do?

Well, women be warned as a new study has linked sleeping with the light or the TV on with putting on weight.

Sure we know we shouldn't really be scrolling Insta before bed, mainly because the blue light can stop us feeling sleepy, but new research has now uncovered a link between exposure to sleeping with artificial light and weight gain in women.

The study, by scientists at the National Institutes of Health and published in JAMA Internal Medicine, gathered self-reported data from nearly 44,000 women, aged 35 to 74.

Using information including weight, height, BMI and waist and hip circumference at the start of the study and follow-up figures five years later, researchers studied obesity and weight gain in women exposed to artificial light at night versus women who slept in dark rooms.

The results revealed that women who slept with a light on were 17% more likely to gain 11 pounds or more over five years.

And according to study authors the level of artificial light women were exposed to at night had a big impact.

Though a small nightlight wasn't linked to weight gain, those who slept with a television or light on were 17% more likely to have put on 5kg or more in just five years.

Sleeping with the light or TV on was also linked to a BMI increase of at least 10%, and a higher risk of being overweight or obese, compared with being exposed to no artificial light during snooze time.

Women who sleep with the light on may be more at risk of putting on weight [Photo: Getty] More

While the study doesn't prove that sleeping with a light on causes weight gain, it suggests the two may be linked.

"Turning off the light while sleeping may be a useful tool for reducing a possibility of weight gain and becoming overweight or obese," lead author Dr Yong-Moon Mark Park, from the National Institute of Environmental Health Sciences told Webmd.

Artificial light has been known to disrupt melatonin, the hormone that promotes sleep, as well as the body's natural circadian rhythm.

"It also may disturb day-to-day variations of stress hormones and affect other metabolic processes in ways that contribute to weight gain," Park continues.

Snoozing with the light on might also result in poorer and shorter sleep, which could lead us to to exercise less and eat more, while making less healthy choices, Dr Park added.

The findings didn't change when researchers accounted for women's diet and physical activity either, which added to the suggestion that lights-on during sleep may be an important factor in weight gain.

The study authors now believe the research could be useful in terms of implementing a public health strategy to reduce obesity incidence in women.

"Unhealthy high-calorie diet and sedentary behaviours have been the most commonly cited factors to explain the continuing rise in obesity," Dr Park said.

Story continues