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Have you been spending too much time glued to your television or computer screens late at night? Exposure to artificial light at night is directly related to depression. Read on to find out how watching TV late at night could trigger signs of depression.
Numerous studies have been conducted to prove a direct correlation between late night TV/computer sessions and depression. Scientists have warned that viewing too much of TV can cause depression. The U.S. Department of Defense recently funded a study conducted by the neuroscientists from the Ohio State University Medical Center to understand the repercussions of exposure to artificial lights at night, on human beings.
The study was led by T A Bedrosian and his fellow neuroscientists and subsequently published in a journal known as ‘Molecular Psychiatry’.

The study confirms the increased risk of depression in human beings on exposure to artificial dim light or artificial light at night (LAN). For the study, hamsters were subjected to artificial dim light for a period of four weeks (which is comparable to watching a television screen in a dark room) and the reaction on their brains was studied. The results were compared to a control group which was exposed to a normal day-night cycle. It was observed that chronic dim light at night causes reversible depression-type phenotype. The exposed hamsters were found to be less active and showed lower interest in drinking sugar water. Both of these symptoms are comparable to the signs of depression in human beings.

The study found that this specific condition can be reversed by avoiding excess exposure to dim light at night. The study found that the effects of artificial dim light at night are more pronounced in women and the exposure can trigger the risk of breast cancer, mood swings, and obesity in women.

The study is based on the fact that the prevalence of depression in the society has increased many-fold in the last couple of decades due to the changes in the environmental factors and our life styles. Artificial night light triggers depression-like symptoms such as lower hippocampal expression of the neurotropic factor gene, enhanced gene expression of tumor necrosis factor (TNF), and lower dendritic spine density.
Tumor necrosis factor is a chemical messenger that becomes active when the body is either injured or infected and is responsible for causing inflammation to repair the damage done to the body. Studies have shown a strong linkage between chronic inflammation and depression. The brain activity of the exposed hamsters seemed to be similar to the brain activity of the people suffering from depression.

It was also found that the effects of the exposure to dim light at night could be blocked by a drug which prevented the expression of depression-like symptoms, though not in totality. The exposed hamsters still showed a reduced density of dendritic spine hair-like growths on the brains cells for sending chemical messages.

The researchers have found that the overall symptoms of exposure to artificial dim light at night are completely reversible. When the exposed hamsters were subjected to the normal day-night cycle, the TNF levels as well as the density of the dendritic spines returned to their normal levels.
Continue reading after recommendations

  • “Chronic dim light at night provokes reversible depression-like phenotype: possible role for TNF”, by Bedrosian TA, et al. Published in the July 2012 issue of Molecular Psychiatry, accessed on August 17, 2012.
  • “Life Without TV? Cultivation Theory and Psychosocial Health Characteristics of Television-Free Individuals and Their Television-Viewing Counterparts”, by Jon Hammermeister, et al. Published in the 2005 Issue of Health Communication, accessed on August 17, 2012.
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