MYSTERY OF SLEEP.

Otago Daily Times, Issue 19994, 11 January 1927, Page 5

MYSTERY OF SLEEP.

RECENT HYPOTHESES,

The nature of sleep has never been satisfactorily determined. Professor J. A. Thomson, in the Empire Review, admits that it does not carry us far to say it is ‘‘an established rhythm, a state of partial fatigue in the nerve-centres, during which recuperation occurs, probably associated with the removal of waste products or toxins.” It is “natural,” we say, that rest should alternate with activity. Yet as we repeat this the difficulty arises in our mind that many animals, most animals, indeed, do not sleep at all; that many parts of our body, such as heart and lungs, food canal, and kidneys go on doing their work as we sleep; that our spinal cord must be a very light sleeper, and that the “breathing centre” in our medulla does not seem to need a rest all the days of our life. With few exceptions only the higher animals seem to require sleep. Many indulge in various degrees of coma, rest, and hibernation. In sleep all the normal functions continue. Dogs and horses are genuine sleepers; guinea pigs probably never sleep. Professor Hempelmann says that sleep is a tax on having a really fine fore-brain. The less intellectual the animal the less sleep it needs. Professor Thomson says that it is difficult to generalise. Mayhe sleep is an auto-intoxication, induced by fatigue toxins produced by the higher nerve centres. Some clever men need little sleep. Yet it seems certain that sleep is a tax exacted by the active mind on the body. “And it is of some interest,” adds Professor Thomson, “that sleeping apes, dogs, cats, horses, and the like utter sounds and make movements the like of which in man’s ease would be regarded as indicative of dreaming, a more or less unregulated activity of alert minds when the hulk of the body is asleep.”