With obesity and the diseases that it causes on the rise in the Western world, many doctors and researchers struggle to find the root causes of this epidemic. At the same time, losing weight can be a personal struggle for the more than half of American adults who simply have too much body fat. New research suggests that dim light at night, which is common in our light polluted world, may be contributing to the ever-expanding American waistline.
Light and Your Circadian Rhythm
Although our bodies have internal clocks that regulate our circadian rhythm even in the absence of external cues, we also set our clocks partly by cues from the outside world. Light is a major circadian cue. When our retinas sense light, the message is passed to the suprachiasmatic nucleus of the hypothalamus of our brains. The suprachiasmatic nucleus in turn tells the pineal gland not to make melatonin.
Melatonin is a hormone that supports sleep and the many cell activities that occur during sleep. When we are exposed to even small amounts of light, we make less melatonin. This is fine during the day when we need to be awake. However, it can be detrimental at night when our bodies need melatonin to help us get the high-quality sleep we need. With years of exposure to light at night, several cell processes including metabolism may be affected.
The Problem of Light Pollution
Light pollution is a very real health problem for people who live in areas where there are nearby sources of light such as street lamps and lighted parking lots. This light is a nuisance, keeping us awake and preventing us from seeing the stars. However, it also presents a constant lower level of interference with our circadian rhythm. People who are exposed to light at night, a group that includes much of the population of North America, may see that their metabolism suffers over time. This can have very real effects on the average weight of the population in areas where light is constant at all hours of the day.
Constant Dim Light at Night: A Cause of Obesity?
According to scientific research, the metabolic effects of dim light at night may have very real health consequences. Oscillating cells in our brain maintain our circadian rhythm. This activity is lessened by constant exposure to light. The result is that many metabolic processes in our cells are uncoordinated and do not run as efficiently. Over time, this lower metabolic rate leads to physical symptoms such as weight gain, fatigue and even a lower body temperature.
This may lead many people to wonder: Do diet and exercise aid in weight loss as most doctors claim? These are still very important factors in your weight. However, we live in a world with ample temptation to make the wrong lifestyle choices. Exposure to dim light at night appears to amplify the effects of bad choices, causing us to gain more weight and suffer more inflammation than we would if we slept in total dark. Nighttime light also appears to stimulate eating at odd hours, leading to a higher overall caloric intake and the resulting higher body mass. For many people, the nighttime snack is a major contributor to their expanding waistline and a difficult habit to curb.
Maintaining a healthy circadian rhythm is part of a healthy lifestyle. If you find that you are having trouble sleeping or trouble keeping the pounds off, limiting nighttime light exposure may be an effective first step to sleeping better and revving up your metabolism. Light-blocking curtains, melatonin supplements and other measures that correct the circadian rhythm may help you to attain the active metabolism and energy that you need to be your fittest, healthiest self.
This concept of sleeping in deep darkness can be carried too far: how did people sleep in the million years since they are around on this planet? When they slept in primitive shelters, for sure they were exposed to the stars in the sky, and the moon. They didn't have a problem sleeping I assume.
It would behoove people to do some daily exercises so they get physical tired and to expose themselves less to computers, ipads, and smart phones...