About 60 years ago researchers discovered the phenomenon of paradoxical (REM) sleep, which is when dreams occur. They called it paradoxical because the pronounced activation of the brain during this period of sleep, comparable with the activation of the brain during the most intense wakefulness, is combined in a paradoxical way with maximum relaxation of the musculature. It wasn’t long before they found that in both humans and animals paradoxical sleep occurs with strict regularity (4 to 5 times a night in humans) and that the brain resists any attempt at artificially preventing this type of sleep from happening. Over the past few decades the science of sleep has developed extensively, the number of journal articles and monographs expands every year, but at the same time we have also seen a growth in the number of facts which have yet to receive adequate scientific explanation and which, at first sight, appear to contradict each other. In what is in itself a paradox, the leading researchers try to avoid discussing these contradictions and it seems as though there is an unspoken agreement to tiptoe past them in their publications. This conspiracy of silence is becoming a danger to further scientific development, because science is not, after all, simply a list of facts, but their explanation and organisation into a particular body of opinion. This was why the organizing committee of the World Congress on Sleep held in September 1995 in the Bahamas readily accepted Professor Vladimir Kovalzon’s suggestion to hold a special session on the “Paradoxes of Paradoxical Sleep” within the framework of the Congress. Professor Michel Jouvet, the world’s undisputed leading authority on the science of sleep, and I were asked to moderate the discussion, which was one of the most representative at the Congress in the range of its participants.
Among those taking part was the President of the Congress, Professor Allan Rechtschaffen, whose atlas of the analysis of sleep structure is used worldwide. In his celebrated Chicago laboratory Professor Rechtschaffen carried out experiments on animals involving deprivation (suppression) of all sleep and paradoxical sleep. He found that an animal deprived of paradoxical sleep will inevitably die if it is placed on a small wooden platform completely surrounded by water, so rendering active behaviour impossible. At the same time, the Chicago researchers were unable to establish a specific cause of death. These results were all the more surprising in the light of findings by Professor Kovalzon. He found that complete deprivation of paradoxical sleep, if carried out not on water but with the help of direct irritation of the brain in conditions where movement was free, did not produce catastrophic consequences. The problem becomes even more complex if we take into account that depriving depressive patients of paradoxical sleep not only does not lead to negative results, but is very often even beneficial in alleviating their depression. Naturally, human patients do not undergo as prolonged a deprivation of paradoxical sleep as animals in experiments, but in this particular case the important thing is that the tendencies develop in opposite directions: in deprivation of paradoxical sleep using the platform on water method there is a tendency towards a lowering of resistance and death, the effect of deprivation using Kovalzon’s method is neutral, while depriving depressives of paradoxical sleep and dreams has a therapeutic effect.
So, does the organism need paradoxical sleep, is it always needed in the same way and if it is needed, then why? Data from philo- and ontogenesis provides significant input into understanding this contradiction. According to the classic studies, the first evidence of paradoxical sleep is seen in birds. It is absent in more primitive types of animal and it reaches its maximum development in the higher mammals and man. Consequently, the higher an animal’s place on the hierarchical ladder of intellectual development, the more paradoxical sleep it experiences.
But here, too, we encounter a paradox. Even a highly developed animal like the dolphin, whose brain power is second only to humans, either has no paradoxical sleep, or experiences it in tiny amounts. This data was provided by Dr. Lev Mukhametov, another participant in the Bahamas session. If a dolphin can do without paradoxical sleep, it means there is no correlation between the level of brain development and the need for paradoxical sleep. The same conclusion, at first sight, derives from data on ontogenesis: paradoxical sleep is present in especially large amounts soon after a child is born, when it occupies from 40% to 50% of total sleep, before diminishing with age to half that. Thus, the dynamic of paradoxical sleep in ontogenesis is opposite to its dynamic in philogenesis, which also calls for explanation.
Other participants in our discussion were Professor Rosalind Cartwright of Chicago and one of the leaders of the Boston group of researchers, Ramon Greenberg. Both these scholars have played pioneering roles in the study of the role of paradoxical sleep in the human psyche. They have shown convincingly that in a healthy person paradoxical sleep and the dreaming connected with it ensure adaptation to emotional stress, play an important role in mechanisms of psychological defence, and help the absorption of unfamiliar and traumatising information which contradicts past experience. According to Greenberg, during dreaming there is an adjustment, as it were, of ‘uncomfortable’ information that conflicts with familiar conceptions and modes of behaviour to pre-existing mechanisms of psychological defence. Experiments with deprivation of paradoxical sleep conducted in their laboratories confirmed that depriving a person of this phase of sleep leads to changes in the whole hierarchy of psychological defence, to a strengthening of repression, to psychological disadaptation.
This way of looking at the function of paradoxical sleep helps explain the increased need for this type of sleep in depression, which is marked by the early appearance of the first episode of paradoxical sleep (sometimes a few minutes after falling asleep instead of the usual 80 to100 minutes), and in some cases by an increase, too, in its overall proportion of a night’s sleep. However, such a view of paradoxical sleep having a defensive function obviously contradicts the findings cited earlier of the the therapeutic action of depriving a person of it in cases of depression: if this sleep is so important for psychological adaptation and its need in depression is increased, then how does suppressing it help free a person from depression?
Furthermore, there would seem to be only one conclusion from theories on the adaptive function of paradoxical sleep and dreams during emotional stress: that under conditions of stress paradoxical sleep must increase and adaptation is possible only if such an increase takes place. Experimental research, however, reveals a significantly more complex picture: in some cases among both humans and animals stress does lead to an increase in paradoxical sleep, but in other cases it diminishes and, what’s more, with very good results – with success in overcoming the stressful situation. An increase or decrease in paradoxical sleep does not depend upon the character of the stress: one and the same stress can provoke an increase in some subjects and a decrease in others, with the consequent result that, seen as a whole, the effect for the group may appear as zero.
What factors determine a change in sleep during stress and how is the change connected with the function of paradoxical sleep? That question remains open.
The role played by paradoxical sleep in the absorption of new information, in learning and memorising is very complex. On one hand, it has been shown that paradoxical sleep has no significant role to play in memorising material that does not contradict past experience and does not need creative processing: paradoxical sleep does not increase in the process of such learning and the absorption of such information does not suffer if a person is deprived of it. Paradoxical sleep is needed, though, to memorise unusual information which a person is initially unprepared to absorb: only after paradoxical sleep increases does the critical breakthrough in the learning process occur, while deprivation prevents the achievement of real success.
On the other hand, however, we know that a state of heightened creativity while solving tasks which are important to a person and which require an innovative approach is often accompanied by a decrease in the need for sleep. Sleep becomes shorter, mainly because of a decrease in the length of paradoxical sleep. Stimulants of the central nervous system, such as amphetamines, improve memorising, assist learning and, at the same time, suppress paradoxical sleep. Finally, as another of the participants in the discussion, the Canadian psychologist Carlyle Smith, showed in many studies, an increase in paradoxical sleep occurs not only during the process of learning, before the new material is fixed in the memory, but also for some time after it has been fixed. The reason for this increase remains rather unclear: if paradoxical sleep is needed to fix material in the memory, then the need for it should diminish after the process is complete.
There was one more serious question raised during this fascinating session: can we say that paradoxical sleep always carries out one and the same function? Can we speak of qualitative differences between functionally complete and functionally incomplete paradoxical sleep? I proposed this hypothesis many years ago on the basis of the results of my own research: it showed that paradoxical sleep in emotionally highly sensitive, but healthy people was filled with vivid dreams: in stress situations their number increased and they became more vivid and unusual, while at the same physical health was maintained. At the same time, subjects suffering from mental and psychosomatic illnesses, despite their increased emotional sensitivity and vulnerability in comparison with healthy people, experienced fewer dreams which were less vivid and detailed, with few images and events. A paucity of dreams was accompanied by physiological differences: the pulse rate during this stage of sleep became less markedly higher in comparison with healthy subjects, and the electrical resistance of the skin dropped. This data was confirmed later in other laboratories elsewhere in the world, in particular by one of the participants in our discussion, Professor Wallace Mendelson. He also demonstrated that in the process of successfully treating the mentally ill the number of reported dreams increased, which may be evidence of the restoration of the functional possibilities of paradoxical sleep.
During the discussion I suggested that the notion of functionally complete and functionally incomplete paradoxical sleep in combination with the concept of search activity may help eliminate many of the contradictions I have mentioned. I have said a great deal about the concept of search activity in this book, and so I will only briefly repeat its basic hypotheses here.
- Search activity is activity directed at changing a situation (or changing an attitude towards it) without a certain prognosis of the result, but taking it constantly into account. The process of search activity in itself, regardless of the final result, increases the organism’s resistance to illness and stress.
- Renunciation of search creates the conditions for lowered resistance to stress and for the development of illness.
- REM (paradoxical) sleep assists the restoration of search activity (at least on the level of mental activity in dreams) and compensates for a state of renunciation of search.
- Behaviour during wakefulness, including pronounced search activity, reduces the need of the organism for REM sleep, whereas renunciation of search increases the organism’s requirement for this phase of sleep.
One of the very strong arguments in favour of the concept comes in the results of an experiment carried out by prominent American physiologist, Professor Adrian Morrison, another of our participants. He has shown that if you destroy the neurons in an animal’s brain that are responsible for the fall in muscle tone during paradoxical sleep, so that as a result muscle tone does not drop, the animal is taking part, as it were, in its dreams and engaging in complex behaviour which, according to Professor Morrison, can most precisely be classified as investigative-search behaviour. Let us look at how this concept can help resolve the paradoxes.
Depriving an animal of paradoxical sleep on a small wooden platform surrounded by water creates conditions which block active search behaviour during wakefulness and, at the same time, prevent the animal from compensating for this state in paradoxical sleep. Two factors are in play simultaneously: a state is created that increases the need for paradoxical sleep, while preventing this need from being satisfied. A chronic deficit of search activity leads to the death of the animal.
At the same time, deprivation of paradoxical sleep by stimulating the brain when there is freedom of behaviour is not accompanied by an increased need for this stage of sleep (there is no renunciation of search), and so there is no fatal outcome.
Depressives experience renunciation of search and increased need for paradoxical sleep. But even in those cases where paradoxical sleep is increased, their need is not satisfied because the quality of the paradoxical sleep is not good enough. Further, the dreams of depressives are often dominated by themes and moods that correspond to the reaction of capitulation in wakefulness, and this reinforces the renunciation of search. Eliminating such dreams by deprivation of paradoxical sleep or all sleep can have a positive effect. Here we need to take the following circumstance into account: for a depressive doing without sleep is a hard and unfamiliar task, which requires a very significant mobilization of resources on his part. And the very fact that he can cope with this (when he fails most of the other tasks life presents him with) raises his self-esteem, his feeling of control over the situation, and has a positive effect. The following clinical procedure was suggested: shift the patient’s sleep pattern from night and morning (when there is a lot of REM sleep) to afternoon and evening (when REM is almost absent, and there is a predominance of SW sleep, which enables the functions of memory and attentiveness). This approach has already provided good results.
Data from philo- and ontogenesis not only do not contradict the concept, but fit in with it well. Paradoxical sleep must first appear at a fairly high level on the philogenetic ladder, when the brain mechanisms of search activity have matured, making it possible. On the other hand, the early stages of ontogenesis in highly developed animals are characterised by helplessness and dependency on parents, stages at which renunciation is easily formed and entrenched, so that a mechanism to compensate for this state is especially needed. Data on the absence of paradoxical sleep in dolphins is extremely interesting in this respect. This animal is constantly in movement, actively observing its surroundings and interacting with them. Only one hemisphere is asleep at any one time, while the other is awake and engaged in active behaviour. With search activity present round the clock there is simply no need for REM sleep. Unless a dolphin has the possibility of an active life and establishes an active friendship with an experimenter, it will die very quickly, since it lacks the defence mechanisms that compensate for renunciation of search.
Changes in sleep under stress are determined by how a person reacts to a stressful situation. If his behaviour is dominated by search activity, even if accompanied by unpleasant emotional experiences, the need for paradoxical sleep diminishes, and its proportion of night-time sleep is reduced without any damage to health. If his behaviour reflects a renunciation of search, the need for paradoxical sleep grows, but, depending on the person’s adaptive capabilities, this need may be satisfied or not. In the first instance, the length of paradoxical sleep increases, as does the number of dreams in which the person engages in active behaviour. In the second, paradoxical sleep may even decrease in length, while if it does increase, there may not be enough dreams and the person’s behaviour in them is passive.
Renunciation of search puts a brake on all mental functions: memory, creative activity and so on. It turns out that encountering new and unfamiliar circumstances and tasks makes the risk of renunciation of search very high. For this reason, paradoxical sleep, which helps eliminate this state, can have an influence, indirectly rather than directly, by removing an obstacle in the form of renunciation of search precisely during the process of learning complex tasks. What the role of paradoxical sleep is in the later stages of fixing information still remains to be discovered, but even in this area the findings we have do not contradict the concept of search activity.
