Increased Delta/Beta Ratio Index in NREM3 Sleep as a Potential Electrophysiological Marker of Reverse Sleep State Misperception in Patients with Early-Stage Schizophrenia

Sleep state misperception describes a mismatch between subjective and objective sleep parameters. While insomnia patients typically overestimate sleep onset latency (SOL) and wake after sleep onset, and underestimate total sleep time (TST), the opposite pattern—reverse misperception—has been reported in schizophrenia but remains poorly characterized. This study examined reverse sleep misperception in early-stage schizophrenia and its potential link to the delta/beta ratio (DBR), a marker of cortical arousal. Twenty patients with early-stage schizophrenia (mean age 25.0 ± 5.7 years; 7 women) and twenty matched healthy controls (HC) underwent video-polysomnography and subjective sleep assessment. Quantitative EEG analysis during NREM3 evaluated delta, theta, alpha, beta power, and DBR. Patients overestimated TST (objective 446.2 min vs. estimated 489.0 min), whereas HC underestimated it (458.5 min vs. 433.5 min; p < 0.05). For SOL, patients overestimated (27.8 min vs. 49.3 min) more than HC (21.6 min vs. 29.5 min; p < 0.05). The sleep perception discrepancy index differed significantly between groups. Spectral analysis showed increased delta power in the left temporoparietal region and reduced beta power in centroparietal areas in patients, resulting in a higher DBR in the temporoparietooccipital region during NREM3. These electrophysiological differences may underlie reverse sleep misperception. Findings align with reports from chronic schizophrenia, suggesting misperception may be a core feature of the disorder. Further studies should assess its presence in at-risk populations and unaffected first-degree relatives. Clinically, awareness of reverse misperception is important when evaluating sleep in schizophrenia.