Chronic dim light triggers temporary brain changes in animals
Psychiatrists sometimes prescribe light therapy to treat a form of depression in people who get too little morning sun. But too much light at other times may actually trigger such mood disorders. Chronic exposure to light at night unleashes depression, a new study finds — at least in animals.
The new data confirm observations from studies of people who work night shifts, says Richard Stevens of the University of Connecticut Health Center in Farmington. Mood disorders join a growing list of problems — including cancer, obesity and diabetes — that can occur when light throws life out of balance by disrupting the biological clock and its timing of daily rhythms.
In the new study, appearing online July 24 in Molecular Psychiatry, Tracy Bedrosian, Zachary Weil and Randy Nelson of Ohio State University exposed Siberian hamsters to normal light and dark cycles for four weeks. For the next four weeks, half of the animals remained on this schedule