CHAPTER XV.

INSUFFICIENT SLEEP.

Conditions of the brain which are supposed to produce sleep-- Congested state of the blood-vessels--An anaemic state-- Suffering when a person is for any cause deprived of sleep-- Persons usually sleep too little rather than too much-- Physiological reasons why children require more sleep than adults--They generally sleep too little, especially when living in cities--The importance of sleep for the brain learned from its universality in nature and especially from the functions of other portions of the body--In this state it recuperates its exhausted energies and stores them up for use when in a state of activity--Inability to sleep a precursor of insanity 223