|Emma McGowan NatureCity author & contributor|
Previous studies have shown that exposure to light can influence sleep and circadian timing, two things that influence weight regulation. Now, a new study has found that exposure to early morning light helps regulate the circadian rhythm and is associated with lower BMI.
Participants in the study included 54 people with an average age of 30. They wore wrist actigraphy monitors that recorded and measured their light exposure and sleep patterns for seven days. They also recorded their caloric intake in food logs.
At the conclusion of the study, the researchers found that morning light was associated with a 20% and 34.7% change in a person’s BMI. This held regardless of physical activity, caloric intake, sleep timing, age, or season.
The researchers theorize that this effect can be traced back to the circadian rhythm, also referred to as the body’s internal clock. Our bodies are programmed to expect light in the mornings and can get out of sync if not exposed to enough light in the morning. This can have alter metabolism and lead to weight gain.
The researchers emphasized that even people who rise early may not be getting enough light, as most Americans live in spaces that do not have a lot of natural light.
Researchers from Northwestern Medicine conducted the study. It was published on April 2, 2014, in the journal PLoS One.
This is the first study of its kind to examine the correlation between light exposure and BMI. However, people looking to lower their BMI should also consider eating probiotic cheese, dark chocolate, and foods that are high in calcium, as all of those have been linked with lower BMI.