Constant Light at Night Leads to Depression in Mice
Researchers from Ohio State University recently began a new study designed to find a correlation between depression and expose to light. The study involved three sets of mice being exposed to different schedules of lightness and darkness. The first group underwent constant light for 24 hours a day. The second group underwent the same light schedule but had a tunnel where they could escape to for darkness. The last group, the control group, was on a normal light/dark schedule where they were housed in light for 16 hours a day and dark for 8 hours a day.
The mice underwent this schedule for three weeks and were tested to measure their anxiety and depression levels. The tests consisted of measuring the mice’s desire to do their usual activities; a loss of this desire is presumed to mean an increase in depression symptoms.
The group of mice that were exposed to light for 24 hours a day showed more symptoms of depression than those of the control group. The group with the option to hide in the tube exhibited fewer symptoms than the 24 hour light group. The mice, housed in constant light, had lower levels of corticosterone, which is a hormone produced by the body linked to anxiety. The results were odd because the relationship between corticosterone and depression are closely related in humans. This can be explained in the mice because of the time of testing at the two week marker, the time of day they were tested, and their nocturnal nature. Due to this theory, researchers have now begun similar tests on diurnal subjects.
These results are very important for humans because humans with overactive lifestyles can be more vulnerable to depression. It is also believed that exposure to artificial lights during the nighttime can be harmful to one’s mental health. I believe this could affect a wide variety of people, such as night workers, people working in or staying in hospitals, and college students pulling “all-nighters”.
Link (Light at Night Linked to Symptoms of Depression in Mice): http://www.sciencedaily.com/releases/2009/10/091021101812.htm
Robin Terry
VTPP 434-502
The mice underwent this schedule for three weeks and were tested to measure their anxiety and depression levels. The tests consisted of measuring the mice’s desire to do their usual activities; a loss of this desire is presumed to mean an increase in depression symptoms.
The group of mice that were exposed to light for 24 hours a day showed more symptoms of depression than those of the control group. The group with the option to hide in the tube exhibited fewer symptoms than the 24 hour light group. The mice, housed in constant light, had lower levels of corticosterone, which is a hormone produced by the body linked to anxiety. The results were odd because the relationship between corticosterone and depression are closely related in humans. This can be explained in the mice because of the time of testing at the two week marker, the time of day they were tested, and their nocturnal nature. Due to this theory, researchers have now begun similar tests on diurnal subjects.
These results are very important for humans because humans with overactive lifestyles can be more vulnerable to depression. It is also believed that exposure to artificial lights during the nighttime can be harmful to one’s mental health. I believe this could affect a wide variety of people, such as night workers, people working in or staying in hospitals, and college students pulling “all-nighters”.
Link (Light at Night Linked to Symptoms of Depression in Mice): http://www.sciencedaily.com/releases/2009/10/091021101812.htm
Robin Terry
VTPP 434-502
posted by Robin Terry at 9:52 PM
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