Microdream neurophenomenology

Abstract

Nightly transitions into sleep are usually uneventful and transpire in the blink of an eye. But in the laboratory these transi-tions afford a unique view of how experience is transformed from the perceptually grounded consciousness of wakefulness to the hallucinatory simulations of dreaming. The present review considers imagery in the sleep-onset transition— " microdreams " in particular—as an alternative object of study to dreaming as traditionally studied in the sleep lab. A focus on microdream phenomenology has thus far proven fruitful in preliminary efforts to (i) develop a classification for dream-ing's core phenomenology (the " oneiragogic spectrum "), (ii) establish a structure for assessing dreaming's multiple memory inputs (" multi-temporal memory sources "), (iii) further Silberer's project for classifying sleep-onset images in relation to waking cognition by revealing two new imagery types (" autosensory imagery, " " exosensory imagery "), and (iv) embed a po-tential understanding of microdreaming processes in a larger explanatory framework (" multisensory integration ap-proach "). Such efforts may help resolve outstanding questions about dream neurophysiology and dreaming's role in mem-ory consolidation during sleep but may also advance discovery in the neuroscience of consciousness more broadly.