Scientists: crash the day and night cycle and reduces the learning leads to depression


15/11/2012

Big changes in biological rhythms associated with shift work or long-haul flights could affect performance and mood. Biological rhythms are known to a large extent depend on the light oscillations.

Drastic changes of the light cycle - the alternation of night and day - directly provoke a depression, and also reduce the ability to think, even if it in no way affects the cycle of wakefulness and sleep and biological rhythms, according to a team of American scientists in their work.

Strong modification of biological rhythms that are specifically related to shift work or long-distance travel can affect the ability of the working man and his mood.

Tara Legeyts with colleagues from Johns Hopkins University decided to analyze whether changes in the light cycle directly affect the learning ability and mood, provided that the rhythm of waking and sleeping is normal.

The researchers conducted an experiment on mice, which to begin accustomed to daily light cycle shifts - 12 hours "night" and "day." After one group of experimental mice, transferred to a seven-cycle, when the darkness gave way to light every three and a half hours. In the control group - the second group - the cycle remained unchanged.

Translated into seven-hour cycle of total sleep time in rodents did not change, nor does it lead to crashes daily (circadian) rhythms of the body.

The paper says - "Regardless of the normal sleep patterns and circadian rhythm in the behavior of mice often slipped signs of depression, and had been shown a reduced ability to learn."

The researchers note that the drugs antidepressants (desipramine or fluoxetine) was reduced in mice learning. Scientists say this indicates that the primary phenomenon is just depression.

Previous studies showed that the failure of the light regime violated the circadian rhythm, which led in turn to sleep deprivation, sleep fail, and after a violation of the working ability. Team Tara Legeyts first proved that the failure mode light itself can adversely affect the performance, without the support of a "mediator" - sleep disorders.


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