EFFECT OF PARTIAL DEPRIVATION ON BOTH DAYTIME VIGILANCE MEASURES AND NOCTURNAL RESPIRATORY DISORDER VARIABLES IN OBSTRUCTIVE SLEEP APNEA SYNDROME

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It has been well known that sleep deprivation brings both elevation of daytime sleepiness and decrease in the tonus of upper airway dilating muscles. However, influence of early partial sleep deprivation on the daytime vigilance and nocturnal respiratory disorder measures in obstructive sleep apnea syndrome (OSAS) has not been well elucidated. In order to clarify this issue, we made a series of the study on the effect of early partial sleep deprivation on the daytime functioning measures and nocturnal sleep variables of OSAS patients.Subjects of this study comprised of both ten untreated OSAS subjects (M:F=7:3, mean age with 29.7 ±3.4 years) and 10 healthy normal controls (M:F=8:2, 29.8±4.5 years) with both normal sleep schedule and normal values of mean sleep latency of maintenance of wakefulness test (MWT) (20 minutes method ; 12 minutes or above). After two weeks of satisfactory nocturnal sleep, the subjects underwent polysomnographic recording (PSG) followed by daytime vigilance ex … More amination including MWT, psychomotor vigilance test (PVT) and event related potentials (P300) under normal sleep condition (subjects slept during the period from 0:00 to 7:00) and condition with early partial sleep deprivation (SD ; sleep period was restricted to the period from 3:00 to 7:00). Order of these conditions was assigned to all the subjects with randomized cross over manner.When comparison of nocturnal sleep structure on PSG between normal condition and recovery night from three days of SD, both group showed higher values of sleep latency and smaller values of both % stage REM and sleep latency on recovery night compared with those on the night of normal condition. As for respiratory disorder variables, both groups showed higher values of apnea hypopnea index on the recovery night. However, significant prolongation of episodes of both apnea and hypopnea as well as significant increase in the nocturnal percutaneous oxygen desaturation(SaO2) on the recovery night was recognized only in the group with OSAS. Among daytime psychophysiological measures, latency of P300 was significantly longer under SD condition in both groups. On the other hand, smaller value of the amplitude of P300 under that condition was recognized only in the group with OSAS. With respect to PVT variables, significant increase in the number of both reaction lapse and false response with SD was recognized only in the group with OSAS. Regarding MWT, mean sleep latency was significantly shorter under SD condition compared with normal condition in the subject two groups. However, rate of decrease in the latency during SD was significantly higher in the group with OSAS compared with healthy control group.From these results, it was revealed that worsening of nocturnal respiratory disorder variables especially prolongation of respiratory events leading to the aggravation of nocturnal oxygen desaturation on the recovery night was more prominent in the group with OSAS. Moreover, increase in objective daytime sleepiness estimated with MWT and deterioration of both cerebral information process manifested on P300 as well as vigilance dependent psychomotor function manifested on PVT during SD was more marked in the OSAS group than in the healthy group. These findings strongly impress that partial sleep deprivation even for three days could act to aggravate respiratory disorder itself and daytime sleepiness as well as its related psychomotor dysfunctioning especially in OSAS patients. We want to emphasize the necessity of both the early treatments of OSAS and the awareness of maintaining correct sleep hygiene in this patients population. Less