“…However, these are not specific for schizophre nia, not all schizophrenic patients have these changes, and a good deal of variability exists across studies in the litera ture [1,2], This may be related to many sources of vari ance affecting sleep physiology [1,3,4], These include age, gender, inpatient/outpatient status, illness severity, and illness duration [1,5], In normal subjects, sleep pat terns change as a function of aging both in regard to sleep continuity and architecture, with reduction in SWS and shortening of REM latency [6][7][8][9][10][11][12][13], as well as intranight distribution of SWS and REM sleep [14,15]. There is some evidence for gender-related differences in sleep parameters in young healthy subjects [16], as well as dur ing healthy aging [17]; nocturnal myoclonus and sleeprelated breathing disorders appear to be more prevalent in elderly males than in females [18], The age-dependent reductions in SWS appear to be more prominent in healthy male seniors [15], In depressive patients, sleep abnormalities tend to worsen with advancing age [ 19] and SWS deficits are more pronounced in males than in females [12,20,21], Apart from introducing potential methodological con founds, gender-and age-related variations in sleep physi ology may have important implications for the patho- physiological substrate of the major psychoses. It is well known that there are gender differences in the age of onset, symptomatology, natural course, treatment re sponse, familial transmission, and outcome, as well as the frequency of neurobiological abnormalities in schizophre nia; specifically, male schizophrenic patients have earlier onset, poorer treatment response, more frequent neuro psychological impairment, brain structural abnormalities on magnetic resonance imaging (MRI), and a more pro tracted course of illness [22][23][24], The gender differences in clinical profiles appear to be seen not only in schizo phrenia, but also in schizoaffective and affective disor ders, though they are less compelling …”