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. Author manuscript; available in PMC: 2015 Sep 9.
Published in final edited form as: Depress Mind Body. 2009;4(3):102–110.

Figure 3.

Figure 3

Etiology and pathology of insomnia and depression.

N.B. The box delineating the homeostatic and circadian factors is highlighted because the neurobiological control mechanisms are not detailed.5-HT: serotonin; SL: sleep latency; TST: total sleep time; VLPO: ventrolateral preoptic area of the hypothalamus; WASO: wake after sleep onset.