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Women are more likely than men to experience seasonal changes in their mood, researchers have found.

The changes, which include depressive symptoms in winter, appear to be independent of factors such as smoking, alcohol use and physical activity.

A University on Glasgow study found low mood and tiredness peaked in winter months.

It also highlighted an increase in anhedonia - the inability to experience pleasure from enjoyable activities.

Analysis of the data of more than 150,000 participants was assessed for evidence of seasonal variation.

The research - published in - found a relationship between shorter days and greater depressive symptoms among women.

However, the research team from the university's institute of health and wellbeing say it may be explained by variations in outdoor temperatures.

Daniel Smith, professor of psychiatry, said: "This very large, population-based study provides evidence of seasonal variations in depressive symptoms which appear to be more pronounced in women than in men."

The condition until recently referred to as seasonal affective disorder affects up to 3% of the general population.

It is also more likely for patients with a history of major depression to experience more symptoms during winter, with new prescriptions of antidepressants also rising.

Researchers scored for "total depressive symptoms" plus symptoms of low mood, anhedonia, tenseness and tiredness.

Associations between the symptoms, day length and average outdoor temperatures were also assessed.

Prof Smith added: "We don't yet fully understand why this should be the case but it was interesting that the changes were independent of social and lifestyle factors, perhaps suggesting a sex-specific biological mechanism.

"Clearly, this is a complex but important area which requires further study.

"Clinicians should be aware of these population-level sex differences in seasonal mood variation, to aid the recognition and treatment of depressive symptoms across the calendar year."