[Chemosensory processing during sleep].

Comparatively little is known about chemosensory processing during sleep. Earlier studies with significant methodological limitations investigated whether olfactory stimulation is processed during sleep at all. The scantness of available data is explained by physiological aspects and methodological difficulties (e.g. rapid adaptation, co-stimulation, etc.). Chemosensory processing during sleep can be assessed by means of event-related potentials, induced arousals or awakenings or by assessing effects on psychological functions. Chemosensory event-related potentials could be demonstrated in 2006. Recent studies with improved methodology have shown that isolated olfactory stimulation does not lead to arousals or awakenings. Finally, the impact of nocturnal olfactory stimulation on learning and emotional dream content could be described.