This relationship remained significant after adjustment for season,' Kent said.

'This new finding that weather may not only affect mood, but also cognition, has significant implications for the treatment of depression, particularly seasonal affective disorder.'

Kent and colleagues speculate that the physiological mechanisms that give rise to seasonal depression may also be involved in sunlight's effect on cognitive function in the context of depressive symptoms.

Cognitive function was assessed by measurement of short-term recall and temporal orientation. In addition to regulating the hormones serotonin and melatonin, light has been shown to also affect brain blood flow, which has in turn been linked to cognitive functions.

These findings were published in the open access journal Environmental Health.