Depressed nocturnal plasma melatonin levels in drug-free paranoid schizophrenics

Palmiero Monteleone, Mario Maj, Mario Fusco, Dargut Kemali, Russel J. Reiter

Research output: Contribution to journalArticlepeer-review

52 Scopus citations


The 24-h profiles of plasma melatonin and cortisol were evaluated in 7 drug-free male paranoid schizophrenics and in 7 healthy subjects matched to the patients for age, sex, body weight, height and season of testing. Blood samples were obtained at 20.00, 22.00, 24.00, 01.00, 02.00, 06.00, 08.00 and 12.00 h. Light was turned off from 21.00 to 07.00 h. Compared with that of the normal controls, the circadian rhythm of plasma melatonin was absent in paranoid schizophrenics (F7,84 = 7.30, p<0.0001; two-way ANOVA with repeated measures) whereas the 24-h profile of plasma cortisol was preserved, although at a slightly higher level (F1,12 = 26.810, p<0.0002). The melatonin/cortisol ratio was significantly higher in healthy subjects than in the schizophrenic patients. A functional relationship between disturbances in the melatonin rhythm especially and schizophrenia may be proposed, although the significance of this relationship remains to be elucidated.

Original languageEnglish (US)
Pages (from-to)77-84
Number of pages8
JournalSchizophrenia research
Issue number1
StatePublished - Apr 1992


  • (Schizophrenia)
  • Cortisol
  • Melatonin
  • Norepinephrine

ASJC Scopus subject areas

  • Psychiatry and Mental health
  • Biological Psychiatry


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