01137nas a2200217   4500008004100000022001400041245003800055210003600093260001200129300001400141490000800155520059500163653002100758653001900779653001300798653000800811653001100819100002100830700002100851856004700872       1994                        eng d  a0006-899300aCircadian rhythm in rat H-reflex.0 aCircadian rhythm in rat Hreflex  c06/1994  a167–1700 v6483 aWe measured soleus H-reflex in the Sprague-Dawley rat as a function of time of day. H-reflex amplitude displayed a marked diurnal variation, even though background EMG and M-response amplitude were stable through the day. The H-reflex was largest in the late morning and smallest around midnight. Thus, its rhythm was opposite in phase to the circadian rhythm found in the primate H-reflex. This rhythm is a potentially confounding factor in studies of motor function. Furthermore, its existence implies that the CNS activity underlying a specific motor performance varies with time of day.10acircadian rhythm10aelectromyogram10aH-Reflex10arat10asoleus1 aChen, Xiang Yang1 aWolpaw, Jonathan  uhttp://www.ncbi.nlm.nih.gov/pubmed/7922520