Table 6.

Studies of prolactin and circadian rhythm in schizophrenia.

Study and authors	Patient sample	Results
Viganò et al., 2001 [103]	13 patients with schizophrenia (5 drug-free)	Abnormal elevation of diurnal prolactin levels found in 10 of 13 patients
Rao et al., 1994 [104]	115 patients with schizophrenia (90 drug-free, 25 on medication); 34 healthy controls	Significant phase advance in prolactin secretion, similar to that seen in depression
Rao et al., 1993 [105]	Patients with schizophrenia (drug-free and on medication); healthy controls	Lower daily mean and amplitude of prolactin secretion in drug-free female patients with schizophrenia compared to controls
Van Cauter et al., 1991 [48]	9 drug-free male patients with schizophrenia; 9 male controls	Threefold enhancement in the sleep-related increase in prolactin in patients compared to controls
Kemali et al., 1985 [106]	23 in-patients with schizophrenia, off drugs for 2 weeks; control in-patients with “neurotic disorders”	No difference in 24-hour prolactin secretion between the two groups
Appelberg et al., 2002 [49]	17 drug-free patients with nonaffective psychosis	Prolactin strongly correlated with REM latency and negatively correlated with REM sleep in patients