Sleep and daytime sleepiness in upper airway resistance syndrome compared to obstructive sleep apnoea syndrome

This study has investigated differences in the nocturnal sleep and daytime sleepiness among patients with obstructive sleep apnoea syndrome (OSAS), up per airway, resistance (UARS), sleep hypopnoea syndrome, and normal control subjects, using sleep scoring and spectral activity analysis of the electr oencephalogram (EEG). Twelve nonobese mates with UARS aged 30-60 yrs were recruited. These subjec ts were strictly matched for age and body mass index with twelve OSAS patie nts, 12 sleep hypopnoea syndrome patients, and 12 normal controls, all male . Daytime sleepiness was evaluated using the Epworth Sleepiness Scale (ESS) and the Multiple Sleep Latency Test (MSLT). The macrostructure of sleep wa s determined using international criteria and spectral analysis of the slee p EEG was obtained from a central lead. The sleep macrostructure of OSAS and UARS patients was significantly differ ent from that of controls. These patients were also sleepier during the day time than controls. Complaints of tiredness and daytime sleepiness, ESS and MSLT scores were similar in the different patient groups. Mild dysmorphia was present in all three patient groups. However, nocturnal sleep was signi ficantly different among the different groups. OSAS patients had significan tly more awake time during sleep than the UARS patients. The spectral activ ity of the total sleep time of the patient groups also differed significant ly from that of controls. When the sleep spectral activity of UARS and OSAS patients were compared, OSAS patients had less slow wave sleep activity th an UARS patients. UARS patients had a significantly higher absolute power i n the 7-9 Hz bandwidth than OSAS patients. The absolute delta power over th e different sleep cycles was also different between controls and patients, and between UARS and OSAS patients. There are clear differences in the macrostructure and spectral activity of sleep between upper airway resistance and obstructive sleep apnoea syndrome patients, demonstrated by differences in the cortical activity recorded in the central lead during sleep. Despite these nocturnal sleep differences, the tests of subjective daytime sleepiness are not significantly different.