Sun and cognitive ability by Marc Sorenson, EdD, Sunlight Institute…
If you have depression, you may also have cognitive impairment, according to older research that I just became aware of. The researchers measured cognitive abilities among approximately 14,000 depressed subjects and then exposed them to either one day of sunlight or two weeks of sunlight. They then determined if cognitive disabilities were associated with the sun they obtained.
The results were impressive: Those who were sun-deprived for two weeks had 2.5 times the risk of being cognitively impaired, compared to those who had sufficient sunlight. A one-day exposure made no significant difference in cognition.
Results of other research, based on a 15-year residential history of varying degrees of sun exposure, has also shown that cognitive impairment in persons who were below the median exposure to sun, was 88% greater than those who were above the median. The researchers mentioned vitamin D as a possible mechanism by which sun positively influenced cognition, but they also remarked that regulation of the circadian rhythm by sunlight could be a factor.
Several other studies showed a close, positive association between vitamin D levels and cognition, and as we know, vitamin D levels in most cases are a surrogate measurement for sun exposure.
The message is to get plenty of sunlight to improve mental clarity. Happy thinking!
 Shia T Kent, Leslie A McClure, William L Crosson, Donna K Arnett, Virginia G Wadley and Nalini Sathiakumar. Effect of sunlight exposure on cognitive function among depressed and non-depressed participants: a REGARDS cross-sectional study. Environmental Health 2009, 8:34
 Kent ST, Kabagambe EK, Wadley VG, Howard VJ, Crosson WL, Al-Hamdan MZ, Judd SE, Peace F, McClure LA. The relationship between long-term sun radiation and cognitive decline in the REGARDS cohort study. Int J Biometeorol. 2014 Apr;58(3):361-70.
By Marc Sorenson, EdD. Sunlight Institute…
Lack of Sun Exposure: Does it cause mental decline? My wife and I conduct church meetings at an assisted-care center, also known as a rest home. In our almost two years at the facility, we note that many of the residents there have lost or are losing their cognitive abilities (abilities to think). It worries us that many of them do not get outdoors often, which probably contributes to both their physical and mental deterioration. It is likely that lack of sun exposure is a key factor, and research from Japan corroborates this view. The researchers had previously reported that elderly individuals with cognitive impairment showed a low frequency of activity. This research assessed whether the type of activity (indoor of outdoor) had different effects on cognition.
The subjects were measured by a mental test known as the mini-mental state examination (MMSE), before being starting the study period. Then, for one year, their activities were measured by an infra-red sensor. At that time they were reevaluated and placed in one of two groups: (1) a cognitive decline group and (2) a normal group. Those whose cognition declined had very few outings away from the facility, compared to the normal group. Those who had 20 or more outings had no decline whatsoever.
The researchers summed up their findings thusly: “This study objectively evaluated the behavior of elderly individuals with infrared sensors and revealed that elderly people who have few occasions to go out tend to show a decrease in cognitive function.” The researchers should have mentioned that those who do not go out have no sun exposure.
It is also known that the risk of being admitted to a nursing home can be predicted by vitamin D levels. In one investigation, those whose serum vitamin D levels were in the deficient category had three-and-one-half times the risk of being admitted to a nursing home as those whose levels were in the highest category. Of course, people with low vitamin D levels are suffering from sun-exposure deficiency. Let’s take care of our elderly by being sure that they enjoy plenty of safe sun exposure.
Safely embracing the sun has so many positive benefits! Be sure your elderly parents and friends have sufficient sun exposure without burning.
 Suzuki T, Murase S. Influence of outdoor activity and indoor activity on cognition decline: use of an infrared sensor to measure activity. Telemed J E Health. 2010 Jul-Aug;16(6):686-90
 Visser, M. et al. Low serum vitamin concentrations of 25 hydroxyvitamin D in older persons and the risk of nursing home admission. Am J Clin Nutr 2006;84:616-22.