California researchers have found a genetic explanation for why some chipper early birds turn glum in the wintertime.

Scientists at the University of California, San Francisco uncovered a gene mutation linked to extreme early risers — people waking as early as 2:30 a.m. and hitting the sack before 8 p.m. The mutation seems to affect how people react to changing light patterns, and also how likely they are to develop seasonal depression.

The study shows that internal clocks are “very largely within our genes,” said Emmanuel Mignot, a professor at the Stanford Center for Sleep Sciences and Medicine, who was not involved in the study. He explained that people’s sleep schedules depend on those internal clocks, also called “circadian rhythms,” and that the study helps explain why the internal clock is so powerful. Those who work night shifts have increased health risks for cancer, psychiatric problems and obesity.


Exercise wards off acute depressions

Vigorous exercise boosts two brain chemicals that help people ward off severe depression, according to a new imaging study by scientists at the University of California, Davis Health System.

It has long been noted that exercise can boost mental acuity and mood. But the underlying biochemical mechanism has remained a mystery.

Researchers say the discovery could lead to new therapeutic insights, improving our understanding of brain metabolism and the chemicals that regulate emotional health.

The research also suggests a role for exercise in boosting the mood of those with major depressive disorder, often characterized by low levels of these brain chemicals. The study is published in the Journal of Neuroscience.

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