Sleep patterns and blood pressure variability in patients with pure autonomic failure.

Sleep patterns and 24-h blood pressure variability were studied in four female patients (age range: 56-82 years) with pure autonomic failure. All patients had severe symptomatic postural hypotension, without neurological deficits. In these patients the following patterns were observed: (i) a reversed diurnal blood pressure pattern, with the highest values observed at sleep onset; (ii) a prolonged sleep latency and increased amount of stage 3 sleep; (iii) difficulty with getting up after awakening in the morning, due to severe postural hypotension; (iv) an absence of prominent respiratory abnormalities during sleep; and (v) a dissociation between respiratory and haemodynamic findings. It is concluded that isolated deficiency of presumed postganglionic autonomic function influences sleep architecture, probably through absence of buffering of diurnal haemodynamic alterations, such as by postural hypotension and its consequences for body fluid volume regulation. This may be of relevance when sleep patterns are studied in other types of autonomic failure with postural hypotension involving central or preganglionic lesions, as in patients with the Shy-Drager syndrome or multiple system atrophy.