Sleep the Need for
Although traditionally it has been accepted that we need a long period of sleep each day to maintain health, some research suggests this may not be so. We might assume that tired muscles and mind need sleep, but the need may only be for rest rather than the unconsciousness of sleep. Dr. Ray Meddis, in his book The Sleep Instinct, suggests that the drive for sleep is an instinct developed in primeval creatures and carried through into human evolution as it still performed a function in early human evolution. Its main purpose, he says, is for animals to remain inert and inconspicuous during hours when they either cannot continue their basic activities such as feeding, mating and rearing young, or to avoid predators. In hibernatory sleep the function was to remain inert while the season made it difficult to feed or rear young. The slowing down of sleep meant not only a conservation of energy but also remaining inconspicuous. He points out that with animals and humans, one seldom ever sees them asleep. This is because they only allow this behaviour in a safe place away from possible harm. Thus mice and rats sleep during the day due to their greater vulnerability in the hours of light.
In each of the animal species there is an inbuilt time period which is built into the patterns of their behaviour. Therefore the giant sloth, on average sleeps 20 hours a day, the cat 14, the mouse and rat 13, the rabbit, man, pig, 8, the elephant 3, and the horse and roe deer only 2.
Meddis says this need for an average 8 hours sleep in humans, is no longer linked to environmental and personal needs as it was in past ages. We no longer need to hide and remain inert during the dark hours to avoid predators, but our inbuilt clock still produces feelings of tiredness and drowsiness. These are linked with our habits rather than to daylight, so if we move to another time zone for instance, as we do when flying to another country, we still tend to feel drowsy or alert at the same time as in the time zone we left.
Why then, if this theory is right, do so many people complain about insomnia? Why don’t they simply get up and enjoy their time awake? Or why, if we miss a nights sleep, do we feel tired and perhaps irritable? And lastly, what about the possible ill effects of dream deprivation?
Meddis answers the first three questions by saying there is for most of us a pleasure in sleeping and the rituals attached to it. For many it is a form of relaxation and withdrawal which refreshes them even if there is no real need for sleep to restore the body. Also, our habits connected with the sleep cycle will still produce drowsiness and withdrawal of attention, yawning stretching reflexes and sore eyes, which we might take for signs of physical exhaustion. The psychological responses connected with the withdrawal of something we enjoy, are convinced we must have for our health, and are habituated to, can explain at least some of the feelings we have if we are deprived of sleep.
The study of true non-somniacs – Meddis’s term for people who do not sleep much each night and do not complain about or suffer as a result of little sleep – by Meddis and others shows that very few people actually manage to sleep for very short periods. Many people who claimed to sleep little were found to poorly judge the periods they slept. Because they woke often during their four or more hours of sleep, they were convinced they had not slept. But some true non-somniacs were found and studied in laboratory surroundings. These were found to exist with an average of about 50 minutes sleep each night. These were healthy happy people who did not complain about not sleeping, but enjoyed their extra hours of waking. Some of them would go for several days and nights with no sleep at all. Then they might sleep and catch up on their average of 50 minutes. During these sleep periods they dreamt in the normal way.
When people are deprived of sleep in laboratory conditions, very few can last longer than four days without sleeping. Meddis gives the figures of only seven men sustaining eight days of sleeplessness, and only one managing to survive for over ten days. There are records of people doing a non-sleeping marathon, but these people were not wired to an encephalograph to see if they lapsed into sleep for short intervals.
The results of being deprived of sleep in this way are first of all a growing urge to rest and sleep. This extreme feeling of fatigue is often accompanied by nausea and irritability. The person may think less rationally and be less in contact with reality. There is a greater tendency to get lost in daydreaming or imagination instead of a focus on external input. A great sense of futility grows in those who are the subjects of the experiment in sleeplessness, and they frequently see the people urging them to stay awake as torturers or sadists. With a few people powerful hallucinations arise. But this is not general.
Strangely, the basic skills are not impaired. Ian Oswald, testing subjects of sleep deprivation, discovered that after three days and nights of sleeplessness, the person’s grip was as strong as ever. Their ability to add and subtract mathematical sums was about the same. Their speed of response to press a key on seeing a light flash was as fast. This showed that despite a huge sense of fatigue, the subject’s muscles were not unduly fatigued, their mind was still capable of rational thought with the same efficiency as when rested, and their responsiveness was not impaired. This surprised psychologists as it had been assumed that sleep was necessary for the avoidance of muscular and brain fatigue. There are effects evident however, and these are to do with repetition of a task or monotony. A sleep deprived person can still easily add and subtract sums, or drive a car across town in challenging traffic, but if the person drives on the motorway or has to repeat a task over and over, the fatigue threatens to overwhelm again. Many mistakes are made with sums, and sleep may claim them while driving. It is continuous concentration on a non stimulating task that is difficult. Anything that stimulates interest or challenge can overcome the fatigue.
Interestingly, Webb – Sleep, The Gentle Tyrant – in testing sleep deprivation with rats, found the stimulus of an electric shock was far less effective in keeping them awake than a positive source of pleasure such as handling or feeding. With electric shock signs of sleepiness were evident after thirty hours. With positive stimuli there were still no signs after four days.
When hallucinations arise, these are almost certainly linked with the physiological and psychological processes that produce dreams. The imagery breaks through powerfully into waking consciousness, and the person usually believes they have heard or seen an exterior event.
Meddis says that considering the difference between lizard brain activity during sleep, and that occurring in mammals, NREM (non-REM) sleep is probably an evolutionary development to deal with the need to self regulate body temperature while sleeping. He points out that while in the womb babies start to dream and show REM sleep, which he calls AS – active sleep, as against QS or quiet sleep, often called NREM. After the baby is born AS still predominates, and QS is only slowly learned. Babies have very little ability to control body temperature, and this has to be gradually learned. This learning curve Meddis connects with the production of QS. The reason being that from research done with animals by people like Parmeggiani, Heller, Glotzbach, Berger and Walker, it has been shown that in an overly cold or hot environment an animal’s heat regulating process does not work during REM or AS sleep. Meddis thinks this is why AS has to be interspersed regularly with QS or NREM sleep, because during QS the body regulates its temperature again, if necessary by shivering or perspiring. When confronting the stress of temperature extremes, AS or dreaming sleep, is suppressed, as the body cannot deal with the temperature by self-regulating. As lizards do not relate to temperature change in the same way, they did not need to intersperse AS with QS.
On the question of why, considering that sleep may not be needed for the body to recuperate, most of us feel exhausted with little sleep, Meddis does not give a convincing response. Considering the scarcity of hard evidence that we need to sleep for physical rejuvenation, people like Evans have seen dreaming as a prime need. But Meddis says the negative influence of dream deprivation has been discounted by recent research. Also, in The Dreaming Brain by J. Allan Hobson, published in 1988, Hobson says – ‘Allan Rechtschaffen and his co-workers in Chicago have convincingly demonstrated that sleep loss can be fatal. Sleep-deprived rats fail to regulate their energy and literally consume themselves metabolically.’ If rats were deprived of sleep, they would naturally be deprived of dreaming, so what is the important issue, dreams or sleep?
We cannot therefore assume there is a commonly agreed stand on what the function of sleep is, even if we are now clear about what happens in some areas when we sleep and dream. See: sleep; science sleep and dreams.