Brain-mind states: Reciprocal variation in thoughts and hallucinations

The exclusion of thinking fr arn recent studies of sleep mentation has hind ered a full appreciation of how cognitive activity differs across the stare s of waking and sleep. To overcome this limitation, this study investigated thoughts and hallucinations using experience sampling, home-based sleep-wa ke monitoring, and formal analyses of the psychological data. The prevalenc e of thoughts decreased gradually from caking through sleep onset and non-R EM sleep, to reach its nadir in REM sleep, whereas hallucinations increased sharply across these states. Furthermore, multiple occurrences of hallucin ations but not of thoughts increased significantly from sleep onset through non-REM sleep, to a peak in REM sleep. This reciprocity in thoughts and ha llucinations might reflect a progressive shift from high to low aminergic-t o-cholinergic neuromodulatory ratios across wake-sleep states, accompanied by an array of changes in the regional activation patterns of the brain.