The need to sleep is a fundamental human given
All human abilities (like paying attention, memory recall and learning) are made worse by poor sleep
There is an intimate relationship between sleep and many psychological conditions — for example, depression, anxiety and psychosis.
We disengage from life, lie down and apparently become oblivious to the outside world for up to eight hours each day. There must me good reason for it.
There are two very distinct kinds of sleep: REM (rapid eye movement sleep when we dream) and non-REM sleep, also called slow wave sleep (SWS).
During REM sleep there is a paralysis of the anti-gravity muscles and the brain's neocortex and emotional centres become highly aroused.
Slow wave sleep is the dynamic, constructive time of physical healing and growth for animal organisms, a recuperative stage where the mind/body system rebuilds itself after a hard day surviving in the world.
By contrast, in REM sleep large amounts of the brain's energy reserves are expending on dreaming. Dreaming is clearly performing a very important function.
REM sleep occupies about twenty-five percent of a healthy adult's sleep time and dreaming in this state is the deepest trance state known.
Sleep is much more than time out from busy schedules; it is essential to the maintenance of physical and psychological health.
We sleep more when we are sick with an infection or develop a fever.
Even when we are asleep without a fever, our immune function works harder than when we are awake.
When we lose sleep we — and those around us — are at high risk from accidents at work and on the road.
All dreams are expressed in the form of sensory metaphors. The reason for this is found in the biology of dreaming and the REM state itself, which all mammals go into. Research indicates that instinctive behaviours are programmed during the REM state in the foetus and the neonate. This is necessarily in the form of incomplete templates for which the animal later identifies analogous sensory components in the real world. These analogical templates give animals the ability to respond to the environment in a flexible way and generate the ability to learn, rather than just react.
We can see this process beautifully when a baby seeks out and sucks on anything similar — analogous to — a nipple, like a finger or rubber teat. Once an instinct-driven pattern is activated and becomes an expectation, it can normally only be deactivated by the actual carrying out of the programmed behaviour by the central nervous system, and this clearly does not give us the flexibility we need to survive.
We can easily see this in our own lives. If we feel angry and let off steam it usually dissipates the anger. But if we were to act out our emotions every time we were emotionally aroused, that would be disastrous. So animals needed to evolve the ability to inhibit arousals when necessary and deactivate them later when they could do no harm. That is why we evolved to dream. During REM sleep unfulfilled emotional expectations left over from the day are run out in the form of metaphors, thus deactivating them and freeing up the brain to deal with the new emotionally arousing events of the following day. Without dreams fulfilling our expectations by acting them out metaphorically we would need a vastly bigger brain.
Dreaming is the deepest trance state we go into. The three essential points to understand about dreaming are -
Dreams are metaphorical translations of waking expectations.
Expectations which cause emotional arousal that is not acted upon during the day to de-arouses the arousal, become dreams during sleep.
Dreaming deactivates that emotional arousal by completing the expectation pattern metaphorically, freeing the brain to respond afresh to each new day.
We all dream for about two hours a night, even though we often don't recall having done so when we wake up the next morning. There is evidence to show that the function of dreaming, which occurs predominantly during REM sleep, is the metaphorical acting out (not the resolving) of unexpressed, emotionally arousing preoccupations, so that the arousal can be discharged and the brain freed up to deal with the concerns of the following day. The process of discharging, and thus completing, patterns of arousal in this way preserves the integrity of our core personality.
In depression, however, this process goes dramatically wrong. Instead of having about 25 per cent (REM) sleep and 75 per cent slow wave sleep (which boosts energy levels in the brain), these proportions become inverted, with the depressed person having far too much REM sleep and too little slow wave sleep. The prolonged negative self examination and introspection which tends to characterise depressed people creates higher than average arousal levels and greater need for discharge during dreams. However, so much discharge activity not only reduces the arousal levels in the brain but also depresses and exhausts it, leaving the dreamer likely to lack motivation the following morning. Indeed, very many depressed people say they wake up from sleep feeling exhausted.
More information about why we dream can be found in the following book by authorsJoe GriffinandIvan Tyrrell.Dreaming Reality: How Dreaming keeps us Sane or can drive us Mad