THE EFFECT OF SLEEP-DEPRIVATION ON SLEEP STATES, BREATHING EVENTS, PERIPHERAL CHEMORESPONSIVENESS AND AROUSAL PROPENSITY IN HEALTHY 3 MONTHOLD INFANTS

We wished to investigate the effects of sleep deprivation on sleep, ar ousal propensity, respiratory events and peripheral chemoresponses in healthy infants, since these effects might be relevant to mechanisms c oncerned with some cases of sudden infant death syndrome. Paired obser vations were made overnight during natural sleep and following sleep d eprivation, in a randomized fashion, in 15 healthy infants aged 78 (7) days (mean (SD)), Polysomnograms were recorded and sleep was scored u sing Anders' criteria, Respiratory events were categorized into centra l, mixed and obstructive apnoeas, Peripheral chemoresponses were measu red during quiet sleep from the respiratory response to two-breath alt ernations in fractional inspiratory oxygen (FI,O-2) (0.42 and 0.00), A rousal propensity was determined from awakening and arousal thresholds to graded photic and auditory stimuli during quiet sleep, and from sp ontaneous awakenings and limb movements. Compared with natural sleep, following sleep deprivation infants maintained a greater proportion of quiet sleep (39 vs 44%). There was no measurable change in arousal pr opensity, During quiet sleep, obstructed breathing events tended to be more common after sleep deprivation (0.1 vs 0 events . h(-1)) and the expiratory time during baseline breathing increased significantly (1. 27 vs 1.58 s) although the decrease in respiratory rate was not signif icant (32 vs 30 breaths . min(-1)). Peripheral chemoresponses altered significantly, alternations in tidal volume/inspiratory time (VT/tI) a s a measure of inspiratory drive increased after sleep deprivation (9 vs 21%). In conclusion, following short-term sleep deprivation in infa ncy, respiratory control alters, peripheral chemoresponsiveness increa ses in magnitude and the timing of baseline breathing alters, without any detectable alteration in arousal propensity, This state may be ass ociated with an increased vulnerability to obstructive respiratory eve nts.