A daily dose of sunshine can boost your overall health. New research shows that sunlight exposure has been linked to better moods, better sleep, and lower lifetime rates of depression.
"Getting bright light during the day is just as important as avoiding it at night," states Sean Cain, psychologist and sleep researcher at Monash University in Melbourne. Previous experiments have shown that artificial light can affect sleep and circadian rhythms.
Cain and his colleagues conducted a new observational study to examine the effects of outdoor light exposure on mood and sleep in more than 400,000 adults in the UK Biobank. This large study collects data on everything, from sleep habits and exercise to health outcomes and medical diagnoses.
Participants were asked questions about their moods, medications, and how much time they spent outside on a typical summer or winter day.
The study found that the average UK adult spent 2.5 hours outside per day, with morning and early bird people spending more time outdoors than night owls.
Research has shown that time spent outdoors and in nature can have a number of health benefits. Part of this may be due to the fact that natural light is the most important environmental cue for the body’s circadian rhythms.
Low mood and sleep problems could be caused by insufficient natural light. This is a leading cause of disability worldwide.
The paper explains that human evolved in an environment where there was a clear distinction between night and day. However, modern environments have blurred the distinction.
People spend most of their waking hours in artificial lighting conditions. This is due to a reduced exposure to sunlight and relatively bright night-time lights.
Because light suppresses sleep-promoting hormone melatonin, this can cause disruptions in sleep. Cain and his team found that almost half of Melbourne's homes had enough light to suppress melatonin 50 percent. However, individual sensitivities can vary greatly.
Cain and his colleagues conducted a new study to determine how daylight hours outside affect mood, sleep and health. This is a topic that has not been as extensively studied as the negative effects of nightlight.
The analysis revealed that getting more sunlight between dawn and dusk is associated with improved mood, better sleep, and lower risk of depression.
An increase in natural light hours was associated with a lower lifetime chance of depression, lower antidepressant use, and higher happiness. The average of four years later, those who reported having better moods and sleeping with more outside light were more likely to do the same again when they were surveyed.
The researchers were able to model the data for around 20,000 people in this manner, which allowed them to evaluate the effects of earlier outdoor time on mood and sleep outcomes. They also controlled for personal habits.
They adjusted for seasonal variations, employment status, exercise, social activity, and sleep quality, all factors that can have an impact on mental health.
Based on our knowledge about light, sleep patterns, moods, and nature, the sunny results were somewhat expected. But, it's encouraging that such a large study has shown the positive effects of spending more time outside.
However, this observational study relies on participants answering questions about their daily routines and health. There may be some differences in people's reported and actual behavior. This research suggests that getting outside can improve mood and sleep quality, but it's not something everyone can do.
Shift workers working against their normal circadian rhythms may find it difficult to soak up the sun during daylight hours. Even for people with other chronotypes or night owls, getting up early to work may not be a good idea.
According to some research, defying your body clock may not be good for your mental health. Another recent study analyzing UK Biobank data found that people who are out of sync with their natural body clock are more likely to experience depression and to have lower levels of wellbeing.
It is fascinating to note the similarities between the study findings regarding depression risk and antidepressant use and the increasing body of evidence suggesting light therapy, particularly when used in conjunction with medication, may be an effective treatment for depression.
The Journal of Affective Disorders published the study.