Effect of age on sleep onset-related changes in respiratory pump and upperairway muscle function

In normal young men, there is an abrupt fall in ventilation ((V) over dot E ), a rise in upper airway resistance (UAR), and falls in the activities of the diaphragm (Di), intercostals (IC), genioglossus (GG), and tensor palati ni (TP) at sleep onset. On waking, there is an abrupt increase in (V) over dot E and fall in UAR and an increase in the activities of Di, IC, GG, and TP. The aim of this study was to determine whether these changes are age de pendent. Nine men aged 20 to 25 yr were compared with nine men aged 42 to 6 7 yr. Airflow, UAR, Di, and IC surface electromyograms (EMGs) and the intra muscular EMGs of GG and TP were recorded. It was found that the falls in IC , GG, and TP at the transition from alpha to theta electroencephalogram (EE G) activity were significantly greater in the older than in the younger men (P < 0.05) and that the fall in Di was also greater, although this was onl y marginally significant (P = 0.15). The rise in GG at theta-to-alpha trans itions was also greater in the older than in the younger men, and there was a trend for TP to be higher.