Arousal responses to olfactory or trigeminal stimulation during sleep.
OBJECTIVE
The interaction of sensory physiology and sleep has been studied for various sensory systems. Nevertheless, the question whether chemosensory (especially olfactory) stimuli may lead to arousals during sleep remains under discussion. Specifically, the central processing of olfactory information shows fundamental differences compared to other sensory systems.


METHODS
Prospective controlled trial.


METHODS
Sleep research facility, University Hospital.


METHODS
Five young healthy, normosmic volunteers.


METHODS
Intranasal chemosensory stimulation during sleep was based on air-dilution olfactometry. For olfactory stimulation H2S (smell of rotten eggs) was used in 4 concentrations (1, 2, 4, and 8 ppm). For trigeminal stimulation CO2 (stinging sensation) was also administered in 4 concentrations (10%, 20%, 40%, and 60% v/v) while odorless stimuli were used for control.


METHODS
Arousal reactions due to chemosensory stimulation were assessed during overnight polysomnography 30 seconds after the presentation of every stimulus during 23 nights of testing.


RESULTS
For olfactory testing, an average number of 703 olfactory stimuli and 157 odorless controls were used for analysis per subject. Even the highest stimulus concentration did not produce an increase in arousal frequency. For trigeminal testing, an average number of 405 stimuli and 79 controls were used for analysis per subject, and an increase in arousal frequency was observed following the increase of stimulus concentration.


CONCLUSIONS
With the present results we were able to demonstrate that, in contrast to trigeminal stimulation, the presentation of a strong but selective olfactory stimulus does not lead to arousals during nocturnal sleep in humans.
Stuck
Boris A
BA
Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Mannheim, Germany. boris.stuck@hno.ma.uni-heidelberg.de
Stieber
Kathrin
K
Frey
Sabine
S
Freiburg
Christopher
C
Hörmann
Karl
K
Maurer
Joachim T
JT
Hummel
Thomas
T
D000328:Adult; D001143:Arousal / Q000502:physiology*; D002245:Carbon Dioxide / Q000494:pharmacology; D002628:Chemoreceptor Cells / Q000502:physiology; D004292:Dominance, Cerebral / Q000502:physiology; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D006801:Humans; D008032:Limbic System / Q000502:physiology; D009297:Nasal Mucosa / Q000294:innervation; D009832:Olfactory Nerve / Q000502:physiology*; D017288:Pain Threshold / Q000502:physiology*; D017286:Polysomnography; D012684:Sensory Thresholds / Q000502:physiology; D012890:Sleep / Q000502:physiology*; D012894:Sleep Stages / Q000502:physiology; D012903:Smell / Q000502:physiology*; D014276:Trigeminal Nerve / Q000502:physiology*
D002245:Carbon Dioxide