A Harvard study identified preliminary results that link blue light to diabetes and possibly obesity.
The researchers put ten people on a schedule that gradually shifted the timing of their circadian rhythms similar to what occurs when you look at a screen or mobile phone. The test subject’s blood sugar levels increased, placing them into a pre-diabetic state. Their levels of leptin, a hormone that keeps people feeling full after a meal, went down.
Here’s a link to the Harvard Study: Link
Here is why. Nighttime exposure to blue light delays the nocturnal melatonin peak (shifting the circadian rhythm) which decreases the production of cortisol. A balanced consistency of cortisol is much needed to increase the body’s metabolism of glucose.
Studies showed that sleeping with a light or a television on in the bedroom is conclusively associated with gaining five kilograms or more. Also, the study showed the body mass index increase of at least 10% over five years among women. This study published in the medical journal JAMA Internal Medicine and concludes Blue Light puts us at a higher risk of being overweight or obese, compared with being exposed to no artificial light during sleep.