Sleep-related breathing disorders. 4. Consequences of sleep disordered breathing.

Sleep disordered breathing is common and may affect up to 24% of men and 9% of women.'There is a continuum in sleep disordered breathing associated with progressively more clinical consequences, from chronic snoring to obstructive sleep hypopnea to severe ob- structive sleep apnoea (OSA).Although certain manifestations of sleep disordered breathing have been described for many years, a wider recognition of the clinical consequences has only occurred in the last decade.Sleep dis- ordered breathing is characterised by recurrent upper airways obstruction which results in episodic asphyxia and interruption of the normal sleep pattern.The clinical consequences of sleep disordered breathing are quite diverse and are usually caused by either the recurrent asphyxia or sleep fragmentation (fig 1). Cardiac consequences SYSTEMIC HYPERTENSIONSystemic blood pressure normally decreases by 5-14% in non-rapid eye movement (non- REM) sleep compared with awake resting