Effects of acute and chronic treatment with trazodone, an antidepressant, on the sleep-wake activity in rats

Pharmacol Res. 1994 Aug-Sep;30(2):105-15. doi: 10.1016/1043-6618(94)80002-2.


Rats were treated with trazodone (2.5 or 10 mg kg-1) twice a day (at light and dark onset) for 11 days, after chronic injection of physiological saline. The sleep-wake activity was recorded for 24 h on the baseline day (saline), on trazodone days 1, 5 and 11, and also on day 12, when physiological saline was injected again (withdrawal day). Trazodone administration increased non-REM sleep. The enhancement of non-REM sleep was dose-related and more pronounced during the dark cycle. The promotion of non-REM sleep was enhanced during the chronic treatment. There were no consistent changes in REM sleep. Spectral analysis of the EEG revealed an increase in slow-wave activity after administration of the high dose (10 mg kg-1) of the drug. It is concluded that trazodone, a clinically effective antidepressant, has a non-REM sleep-promoting effect. It is speculated that the promotion of sleep by trazodone may be mediated by serotonergic mechanisms.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Animals
  • Dose-Response Relationship, Drug
  • Electroencephalography / drug effects
  • Male
  • Rats
  • Sleep / drug effects*
  • Sleep Stages / drug effects
  • Time Factors
  • Trazodone / administration & dosage*
  • Trazodone / pharmacology*
  • Wakefulness / drug effects*


  • Trazodone