Cholinergic REM sleep induction by arecoline in normal subjects: relation to thyroid function.

Serum thyroid hormones and the speed of rapid eye movement (REM) sleep induction by the central muscarinic agonist arecoline were measured in 21 normal volunteers. The arecoline-REM induction latencies had a modestly significant negative correlation with free thyroxine index. This finding is discussed in the light of observations in animal studies that thyroid hormones stimulate central cholinergic neuronal function.