Aims Emil Kraepelin introduced a disorder called “paranoid depression,” but “paranoid” became linked to schizophrenia, not to mood disorders. We made Polysomnographic (PSG) measurement of sleep by schizophrenic patients (acute, paranoid and chronic) to investigate models of sleep disturbances in different types of schizophrenia.
Methods Neurophysiologic measurement of sleep using electroencephalography (EEG), electrooculography (EOG) and electromyography (EMG) was carried out in 30 patients with an acute schizophrenic state (F 23.1 & F 23.2 in ICD-10) and in 30 patients with a chronic/residual schizophrenic state (F 20.5 in ICD-10). Recording of sleep patterns (according to Rechtschaffen & Kales), statistical analysis and estimation of the discriminative models of sleep was made in these two groups of psychotic patients. The Electrophysiological Profile of Sleep (EPS) was derived from these measures and contained 130 variables of nocturnal sleep. Statistical analysis was by step-wise discriminative function analysis.
Results The most discriminative variable in this battery was the Index of Endogenous Periodicity/Perturbation (IEP-P1): IEP-P1=REM-1/NREM-1, where REM-1 and NREM-1 are the first periods of REM and NREM sleep, respectively. Two patterns were seen: (1) The Index of Endogenous Perturbation (IEP-P1) was LOW in the first group which we call the “REM DEFICIT” type of sleep disturbance (with reduction of “REM-1 phase”) in acute schizophrenic states; IEP-P1 <0.3. (2) The IEP-P1 index was HIGH in the second group which we call the “DELTA DEFICIT” type of disturbed sleep (with reduction of “delta-sleep”) in paranoid and chronic (residual) schizophrenia states; IEP-P1 >2.40, very similar to sleep disturbances by affective psychotic disorders!
Conclusions (1) The results of our investigations demonstrate that the Index of endogenous sleep perturbation (IEP-P1) is a highly reliable indicator of sleep disturbance in acute, paranoid and residual schizophrenia states. (2) With this sleep pattern the paranoid schizophrenia become more linked to affective disorders, not to schizophrenia.