SLEEP WITHOUT DREAMS: NREM SLEEP

Biology of NREM sleep

We know there are two different kinds of sleep, and they alternate with each other throughout the night. During REM sleep dream are experienced, and during NREM sleep there are few or no dream at all. When we fall asleep we go through NREM sleep, then RE” sleep; these two combine to form one sleep cycle and we have few sleep cycles throughout the night. In this chapter we are going to study NREM sleep in detail.

In NREM or non-REM sleep there is an absence of rapid e movement as recorded by the electro-oculogram or EOG. The brain waves are also calmer, in contrast to those of REM sleep. During REM sleep, the brain waves are not much different from those the awake state. However, during NREM sleep the brain wav are slow and big and are divided into four stages according to the frequency.

During NREM sleep the mind is in complete rest, and is passive peaceful, and calm. In REM sleep, in contrast, the mind is active’ and explosive, and the whole brain is working to capacity. Some experts report a 40 per cent increase in the blood flow to the brain during REM sleep.

During NREM sleep, the breathing is slow and regular. The blood pressure is lower than when we are awake, and the heart rate also slower as if we are in complete rest. On the other hand, du ‘ REM sleep the breathing is very heavy, and irregular. The blood pressure can be sky-high and the heart rate can be as fast as we had just finished a 100 m race. It has been observed that a heart attack or stroke takes place during sleep at night, it occurs during the REM stage. However, the peak incidence of heart attacks is between 7 a.m. and 11 a.m. in the morning and not during sleep. So you can sleep easy.

What about the muscular system during sleep? During NREM •km the muscles are active and the muscular system is fully engaged with the brain. There are spontaneous movements in the body during NREM sleep. We turn over many times during the night. This movement is important. People who cannot move because of illness such as quadriplegia suffer from bedsores. They need to be turned by nursing staff continuously throughout the 24 hours. The reason is that if the body is not moving during sleep, the skin which is under pressure from the weight of the body will be blanched and the blood supply to that part of the skin will be insufficient. That area of skin will break down and slough off to form a bedsore. So it is important that the body turns automatically during sleep, turning and moving of the limbs prevents the stiff neck and joint pain that most people experience the morning after they en drunk the night before.

REM sleep the muscular system is disengaged, as if a mechanism is preventing the body from moving. This I the physical acting out of dreams. REM sleep is also called ‘paradoxical sleep’; the brain is so active and yet, paradoxically, the body is completely paralysed.

Is NREM sleep unconscious?

NREM sleep represents three-quarters of the time spent in sleep. Although a great deal of study has been carried out on the psychology is, no one has yet studied the psychology of NREM sleep, try to make amends here. Biologists and physiologists classify our state of awareness into two main types, the conscious state and the unconscious state. This grouping should not I with Freud’s concept of the conscious and unconsciouscious state is a state in which we are not aware of anything and from which we are not easily aroused. It includes such experiences as a black-out after a head injury, the complete blank while under general anaesthetic, and so on.

The conscious state, on the other hand, is a state in which we are continuously aware of what goes on around us or of what we are thinking. We can account for all events continuously. So we how we got out of bed in the morning, got dressed, t, went to work, said hello to the pretty secretary, worked hard, had a wonderful lunch with the secretary, went back to the office to work even harder, came home, had dinner, watched to bed (still thinking about the wonderful

lunch) … and then there is a blank, until we get out of bed again the next morning. (For the lady readers, please change ‘pretty secretary’ to ‘handsome assistant’, but note that the pretty secretary here just happens to be my wife!)

An interesting feature of the above is that we are able to give a continuous account until after our thoughts of ‘the wonderful lunch’. A blank follows. We are not unconscious, as we can be aroused easily. However, we are not conscious either, as there is a blank in the continuous account of the day’s event. This blank is NREM sleep, during which there is no thinking, no memory, and no account of what goes on, very much like the blankness we have when undergoing general anaesthetic. NREM sleep is classified under the conscious state because it is arousable, but it is much more like the unconscious state, as we have no thinking or memory and cannot give a continuous account of what goes on.