Did you know that exposure to bright morning sunlight can help you to manage your body weight?
Surprisingly, a new Northwestern Medicine study reports that the timing, intensity and duration of light exposure during the day is linked to weight and fat distribution, the first time this has been shown.
This study included 54 participants (26 males, 28 females) with an average age of 30 years. They wore a wrist monitor that measured their light exposure and sleep parameters for seven days in normal-living conditions. Caloric intake was determined from food logs.
Study participants who had most of their daily exposure to even moderately bright light in the morning had a significantly lower body mass index (BMI) than those who had most of their light exposure later in the day.
This striking influence of morning light exposure on body weight was independent of physical activity level, caloric intake, sleep timing, age or season. It accounted for about 20 percent of a person's BMI.
According to health experts, light is the most potent agent to synchronize the internal body clock that regulates circadian rhythms - which in turn control the energy balance in your body.
The message of this study is that you should get more bright light between the hours of 8 am and noon. In fact, about 20 to 30 minutes of morning light is enough to affect BMI.
If you don't get sufficient light at the right time of day, it may de-synchronize your internal body clock, possibly altering metabolism and leading to weight gain - although the way light affects body fat distribution is not yet fully known and requires further research.
The sad fact is that most people do not get enough natural light in the morning. Also, most of us work in poorly lit environments with about 200 to 300 lux light exposure.
In this study, 500 lux was the minimum threshold for having a lower BMI. Even on a cloudy day, outdoor light is more than 1,000 lux, which is very difficult to achieve with indoor lighting.
The results of this study show that light can potentially be used in weight management programs and emphasize the importance of so-called ‘circadian health’. Just as too much light at night disrupts the body clock, not getting enough light at the appropriate time of day may have the same effect.
Based on these findings, it’s clear that as part of a healthy lifestyle, people should be encouraged to get better exposure to light. Workplaces and schools should have windows. Employees should be encouraged to go outside for lunch or breaks, and indoor lighting should be improved in the school and workplace.
Source: Morning Rays Keep Off the Pounds.