What are the effects of spending time outdoors in daylight on the physical health of older people and family carers : a systematic review protocol

The benefits of spending time outdoors for physical health are well documented. Historically, the benefits of being outdoors and exposing the body to daylight did not become a public health concern until the late 1800s, when daylight became a treatment for rickets and tuberculosis. It was not until the 1970s that the impact of daylight on the physical health of older people became an area of intense interest when vitamin D was discovered as the ‘sunshine vitamin’. Spending times outdoors provides people with direct or indirect exposure to daylight. Daylight is crucial for regulating the body’s circadian rhythms and sleep/wake cycle. Daylight also enables critical chemical reactions in the body, such as regulating melatonin levels and supporting vitamin D metabolism. In older adults, dietary intake of vitamin D from foods is modest so the major source of vitamin D comes from the action of daylight on skin. Amongst other roles, research has demonstrated that adequate vitamin D status (>25nmol/L 25[OH] D) can be an effective method for reducing fractures in older people. The amount of daylight a person is exposed to directly relates to the rate of production of serotonin by the brain. This is significant in relation to psychological wellbeing as serotonin is known to contribute to feelings of health and happiness.