SAD and Being Outdoors
For decades it has been assumed that seasonal affective disorder (SAD) relates only to the amount of light. However, this does not explain the lower levels of SAD among many northern climate cultures such as Eskimos as compared to lower latitude dwellers. SAD, as most know is considered a debilitating disorder causing depression, anxiety, fatigue, and lethargy, there are curious exceptions.
For example, a study from Iceland’s National University Hospital (Maqnusson and Stefansson 1993), found that Icelanders experience lower SAD prevalence than do people on the east coast of the United States. In another study from Turku University’s Central Hospital (Saarijarvi et al. 1999), the prevalence of SAD was higher among women and younger ages, but notably also more prevalent among those with a higher body mass index. These characteristics of course are also consistent with people who are less likely to go outdoors. There are many other studies indicating lower rates of SAD among those who exercise outdoors.
Indoor light ranges from 60 lux at low lamp level to 200 lux in average indoor lighting. The brightest indoor lighting might produce about 1000 lux. Levels of over 1000 lux typically require some sort of daylight.
The typical American gets about 100 lux per day on average, experiencing only quick bursts of any higher lux, and then barely over 1000 lux. 1000 lux is about as much light as is available in the twilight period—just after sunset or just before sunrise. Research on shift workers has confirmed that light above this level for three hours will re-establish sleep cycles and positive moods within 48 hours, while other techniques such as coffee and alarm clocks can take up to eight days to re-establish ones sleep cycle. Levels of over 4000 lux are needed for most endocrine-stimulating functions. Going outside into the sunlight is required for these levels.
Those who get outside and connect with the nature’s combination of waves—visible light, ultraviolet light, geomagnetic sun pulses, the earth’s magnetic pulses and fresh air—are less likely to experience the depression, fatigue and other symptoms experienced by those who do not get outside into nature.
This has been an excerpt from Healthy Sun: Healing with Sunshine and the Myths About Skin Cancer.