Prevalence of sleepiness and its relation to autonomic evidence of arousals and increased inspiratory effort in a community based population of men and women

Degrees of sleep apnoea and daytime sleepiness are quite common in communit y populations. However the relationship between the two is poor, although s leepiness does correlate better with a history of snoring. It has been sugg ested that sleep can be fragmented by upper airways obstructive events, sho rt of full apnoeas or hypopnoeas, and that these events may not provoke ful l cortical arousal, but be detectable through activation of the autonomic s ystem. Failure to detect both these could mask a relationship between 'slee p apnoea' and daytime sleepiness. We have therefore measured sleepiness (Ep worth Sleepiness Scale) in addition to both autonomic 'arousals' and inspir atory effort (using pulse transit time) in 473 men and women at home. Altho ugh sleepiness was related to a history of snoring, it was not significantl y predicted by the measures of autonomic 'arousal', or inspiratory effort. Reported snoring and objectively measured snoring correlated poorly. As in other studies, nocturnal hypoxic dips were correlated with obesity, age, al cohol consumption, drug usage and a history of snoring. These data make it unlikely that sleep fragmentation from subtle variants of sleep apnoea and 'autonomic' (or 'subcortical') arousals are an important source of daytime sleepiness in the community.