(in prescriptions) at bedtime.
Origin of hor. som.
From the Latin word hōrā somnī at the hour of sleep
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
hora somni (before sleep, at bedtime)
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.