I've been advised to pretty much dip my head in cold water either before or after the morning tooth brushing. It's something people apparently do in the privacy of those first moments of the day, and apparently it's neither strange or unusual, and apparently it's perfectly normal.
The object of this exercise is to freshen the face, give a jolt to the system
and rouse the cortex from a condition of sullenness to one of effervescence and
good cheer. After two mornings of conducting his own experiments in this area a
person can begin to wonder at the definition of the word 'normal.'