Washington, July 29 - A lack of sunlight seems to eclipse brain power in depressed people, according to the latest research.

Researchers used weather data from NASA satellites to measure sunlight exposure across the US and linked this information to the prevalence of cognitive impairment in depressed people.

Cognitive impairment or brain fog is defined as unusually poor mental function, associated with confusion, forgetfulness and difficulty.

Shia Kent of the University of Alabama at Birmingham (UAB) led a team of researchers who used cross-sectional data from 14,474 people in the National Institute of Health funded study. They investigated stroke incidence and risk factors and studied associations between depression, cognitive function and sunlight.

'We found that among participants with depression, low exposure to sunlight was associated with a significantly higher predicted probability of cognitive impairment.