Mild hypoxia does not suppress auditory arousal from NREM sleep.
OBJECTIVE
The depressive effects of hypoxia on the central nervous system are well known. The purpose of this study was to determine the influence of mild overnight hypoxia on the ability of healthy individuals to arouse from non-rapid-eye-movement (NREM) sleep to auditory tones.


METHODS
Randomized cross-over.


METHODS
Participants slept in a sound-insulated room with the physiologic recordings and experimental interventions controlled from a separate room.


METHODS
Eleven healthy men aged 18 to 24 years.


METHODS
On separate nights, participants were exposed to mild overnight hypoxia (SaO2 approximately 90%) or medical air in single-blind fashion. During established sleep, subjects were administered 1 of 10 auditory tones (500 Hz, 54-90 dB, 5 seconds duration) via earphones, or a sham tone (recording period with no tone).


RESULTS
The probability and intensity of arousal responses in the 30 seconds following tones or shams were compared between gas conditions and between stage 2 and slow-wave sleep. Arousal probability and intensity increased with tone intensity and were significantly lower during slow-wave compared with stage 2 sleep but were not different between hypoxia and normoxia nights.


CONCLUSIONS
These data suggest that mild overnight hypoxia does not impair the neural mechanisms involved in arousal from sleep to auditory stimuli.
Catcheside
Peter G
PG
Adelaide Institute for Sleep Health, Repatriation General Hospital, Daws Road, Daw Park, SA 5041, Australia. peter.catcheside@rgh.sa.gov.au
Orr
R Stan
RS
Chiong
Siau Chien
SC
Mercer
Jeremy
J
Saunders
Nicholas A
NA
McEvoy
R Douglas
RD
D000293:Adolescent; D000328:Adult; D001307:Auditory Perception / Q000502:physiology*; D002245:Carbon Dioxide / Q000378:metabolism; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000097:blood* / Q000503:physiopathology*; D008297:Male; D010100:Oxygen / Q000378:metabolism; D012720:Severity of Illness Index; D016037:Single-Blind Method; D012890:Sleep / Q000502:physiology; D012894:Sleep Stages / Q000502:physiology*; D013997:Time Factors
D002245:Carbon Dioxide; D010100:Oxygen