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Depression in physiology and medicine refers to a lowering, in particular a reduction in a particular biological variable or the function of an organ. It is in contrast to elevation.

For example, it is possible to refer to "depressed thyroid function" or to a depression of blood flow in a particular area.

Further examples:

• Depression of the central nervous system of an animal may be expressed as drowsiness or sleep, lack of coordination and unconsciousness.

Such physiological depression can in turn lead to Depressed mood and/or clinical depression either through direct means or indirect mechanisms.