Sleeping with the lights on & obesity
Researchers have found a surprising new link between the amount of light in your room at night and weight.
Sleeping in a room with a lot of lights around may be a risk factor for gaining weight.
Researchers looked at three types of light. In general, small night lights in the room were not associated with significant risks.
Participants who slept with a light or a television in the room had a 33% higher chance of developing obesity over the course of the study.
Types of light at night & obesity risk
Those with a light on outside the room had a 20% chance of developing obesity. While the margins of error were large as indicated by the white bars above, the increase in risk was significant for all three categories.
Sleeping with Lights: Waist Width
The clearest effects were seen in waist circumference. Waist circumference is one of the best indicators of cardiovascular health.
Participants who slept with a light or a television in the room had a 22% wider waist circumference than those who did not. Those who slept with a light outside the room, such as a hallway light peeking through the door, had a 16% wider waist circumference.
Shortcomings of BMI
Sleeping with Lights: Weight Gain
In terms of weight gain, only volunteers with a television in the room or a light on in the room had a significant risk of weight gain after multivariable adjustment.
The mechanism behind this surprising finding is still relatively unclear. While sleep is linked to weight loss, these relationships remained even after adjusting for sleep.
One possible mechanism that the researchers brought up was is the potential effect of lights on our hormonal rhythms.
Our sleep cycles are driven by hormones that respond to light. Having the lights on during sleep may disrupt these hormonal cycles, causing us to eat differently and use energy differently. One hormone that may be particularly affected is cortisol, which affects how fat is deposited in the body.
All of these are just theories at this point, we will need further research on this topic to confirm this link.
Additionally, we will need more research to confirm whether turning off lights at night can reduce obesity.
Keys to Health
As with all such studies, correlation does not confirm causation.
However, given the significant results seen, the data does look convincing.
Before knowing for sure, scientists will need to do more research on this topic. If you are concerned about this, it certainly doesn’t hurt to turn off the lights at night. Light gets in the way of good sleep, and good sleep is important for good health.