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Study Objectives: The goal of the study was to seek physiological correlates of lucid dreaming. Lucid dreaming is a dissociated state with aspects of waking and dreaming combined in a way so as to suggest a specific alteration in brain physiology for which we now present preliminary but intriguing evidence. We show that the unusual combination of hallucinatory dream activity and wake-like reflective awareness and agentive control experienced in lucid dreams is paralleled by significant changes in electrophysiology., Design: 19-channel EEG was recorded on up to 5 nights for each participant. Lucid episodes occurred as a result of pre-sleep autosuggestion., Setting: Sleep laboratory of the Neurological Clinic, Frankfurt University., Participants: Six student volunteers who had been trained to become lucid and to signal lucidity through a pattern of horizontal eye movements., Measurements and Results: Results show lucid dreaming to have REM-like power in frequency bands delta and theta, and higher-than-REM activity in the gamma band, the between-states-difference peaking around 40 Hz. Power in the 40 Hz band is strongest in the frontal and frontolateral region. Overall coherence levels are similar in waking and lucid dreaming and significantly higher than in REM sleep, throughout the entire frequency spectrum analyzed. Regarding specific frequency bands, waking is characterized by high coherence in alpha, and lucid dreaming by increased delta and theta band coherence. In lucid dreaming, coherence is largest in frontolateral and frontal areas., Conclusions: Our data show that lucid dreaming constitutes a hybrid state of consciousness with definable and measurable differences from waking and from REM sleep, particularly in frontal areas.

Many previous observers have reported some qualitative similarities between the normal mental state of dreaming and the abnormal mental state of psychosis. Recent psychological, tomographic, electrophysiological, and neurochemical data appear to confirm the functional similarities between these 2 states. In this study, the hypothesis of the dreaming brain as a neurobiological model for psychosis was tested by focusing on cognitive bizarreness, a distinctive property of the dreaming mental state defined by discontinuities and incongruities in the dream plot, thoughts, and feelings. Cognitive bizarreness was measured in written reports of dreams and in verbal reports of waking fantasies in 30 schizophrenics and 30 normal controls. Seven pictures of the Thematic Apperception Test (TAT) were administered as a stimulus to elicit waking fantasies, and all participating subjects were asked to record their dreams upon awakening. A total of 420 waking fantasies plus 244 dream reports were collected to quantify the bizarreness features in the dream and waking state of both subject groups. Two-way analysis of covariance for repeated measures showed that cognitive bizarreness was significantly lower in the TAT stories of normal subjects than in those of schizophrenics and in the dream reports of both groups. The differences between the 2 groups indicated that, under experimental conditions, the waking cognition of schizophrenic subjects shares a common degree of formal cognitive bizarreness with the dream reports of both normal controls and schizophrenics. Though very preliminary, these results support the hypothesis that the dreaming brain could be a useful experimental model for psychosis.

Study Objectives: To describe emotional experience during sleep-onset rapid-eye-movement [(REM) SOREM] sleep and nighttime REM in narcoleptic patients and to relate any differences in REM emotion to the more general abnormalities of this disorder., Design: Awakenings were performed from SOREM (REM at the onset of daytime naps and nighttime sleep) and nighttime emergent (ascending) REM in 15 patients with narcolepsy and from nighttime REM in 9 normal healthy participants. Subjects rated the occurrence and intensity of discrete emotion types for each line in their REM-mentation reports. Fragmentation of REM was measured and related to emoton., Setting: Subjects were studied in their own homes over 2 consecutive days and nights (3 nights for normals) and were monitored by ambulatory polysomnography., Participants: Fifteen patients with narcolepsy, aged 17 to 70 years (mean = 45.3) and 9 normal healthy subjects, aged 31 to 60 years (mean = 43.0)., Results: Emotions were found more often and were more intense in narcoleptic SOREM than in nighttime REM of either narcoleptic or normal subjects, with anxiety/fear exhibiting the strongest increase, followed by joy/elation. Comparing nighttime REM in narcoleptic and normal subjects, narcoleptics were found to have more intense feelings of anxiety/fear and of joy/elation but to have a less frequent experience of surprise and anger. Positive and negative emotions occurred in a balanced fashion in SOREM and nighttime REM in narcoleptic subjects. In the SOREM of narcoleptic patients, high levels of positive emotions, in particular of joy/elation, were associated with a less fragmented (more stable) REM sleep., Conclusion: The REM sleep of patients with narcolepsy affords a unique opportunity to study emotion and to analyze its psychophysiology. Narcolepsy intensifies REM-dream emotion, especially anxiety/fear and joy/elation, and this is most clearly seen during SOREM sleep. The changes in REM emotion of narcoleptic patients could reflect the effect of the fundamental pathology of this disorder upon neurobiologic systems that support cognitive-emotional functions.

Previous studies have demonstrated that the Nightcap home-based sleep-monitoring system can differentiate waking, NREM and REM sleep based on eyelid movements (ELMs) and head movement behavior. The present study aims at determining the reliability of the Nightcap in determining the human sleep onset latency (SOL) as revealed by standard polysomnography (PSG). Four naps were recorded in each of ten normal subjects using both PSG and the Nightcap simultaneously. The Nightcap algorithm scored sleep onset as the first of 4 consecutive 30-sec epochs with less than 5 ELMs. The mean percentage of agreement between the Nightcap and PSG was 93% (k = 0.79), and the average absolute difference was 45 sec (13.3% of SOL(PSG)). SOL(NC) differed by less than 1 min in 85% of onsets. Recordings of EEG activity from 90 sec before and after PSG-identified sleep onsets were subjected to spectral analysis. Changes in spectral power in the theta (4-7 Hz) and alpha (8-12 Hz) frequency bands during the transition into light sleep correlated well with eyelid behavior. However, changes in ELM density predicted sleep onset better than did changes in theta and alpha spectral power. These results suggest that the Nightcap may be a potential alternative to the PSG technique in the assessment of SOL in normal subjects.