According to recent information, sleep deprivation, even a shortening of sleep by 3 hours for one day, can result in a a lowering of the T-cell count of the immune system by as much as 50%. This gives rise to another insight into what may be occurring in the sleep state.

Possibly during daytime activities the brain is busy directing conscious thoughts, perceptions and actions. During sleep all this is suspended, and the brain has time and energy to fulfill the other part of its dual role: to send hormonal messages to other body organs to step up or modify particular physiological activities that had been put on a back-burner during the busy external work schedule of the daytime waking state. Norman Cousins has said that the brain is like a master gland, secreting more hormones than any other. The brain could be the director of the hormonal system, as well as of the nervous system; doing the latter mainly by day and the former predominantly by night.

There may be more involved than reinvigorating and resupplying the immune system, though this is obviously important. The last stages of digestive system function probably occur at night during sleep; many people naturally defecate in the morning, as part of a daily habit. Temperature regulation may be involved, with a low at about 3 a.m. (if we go to sleep about 11 p.m. or midnight), and a high at 6 or 7 a.m. on waking and rising, at least for us “morning people”. The “night people” have a different circadian temperature cycle. The mental performance cycle closely follows the temperature cycle.

These considerations imply that the nervous level is in close contact with the hormonal and immune level (see my essay on Levels of Being in Section IX), and in closer contact during sleep than during waking hours. It is only a guess — but perhaps sleep is required to get back in touch with our inner self after the other half-cycle of intense interaction with the surroundings. Thus sleep is a re-creation of ourselves, even a re-linking (a re-ligion).

Another insight is that different neuro-transmitters go into action during sleep than during wakefulness. During the day, the active neurotransmitters are the amines (epinephrine or adrenaline, dopamine, etc.); during the night the cholines take over (e.g. acetylcholine). The switch that induces sleep brings a whole alternative system of brain functioning into action; and the reverse happens on waking. Sleep paralysis (a horrendous state ofterror when we are awake but unable to move) signifies a state of contention between the amines and the cholines, a sort of a grinding of gears when we fail to engage the clutch.

Finally, it has been found that adenosine (a sugar-base combination) accumulates during wakeful activity, probably as a result of using up the energy-supply chemical ATP (adenosine triphosphate). During sleep, adenosine concentration decreases. So probably the brain’s energy stores are replenished.