Rem Sleep

"The foundation for much of what we know about sleep was gathered approximately 40 years ago by researcher, Michel Jouvet. This French scientist studied the effects of gross brain lesions and brain transections on sleep behavior and related phenomena. It was Jouvet who first suggested that a brainstem region is responsible for the initiation of events that result in the stage of sleep called REM sleep. REM sleep is a stage associated with rapid eye movements, a high degree of brain wave activity, relaxation of large muscles of the body, and increased frequency of dreams. More about the stages of sleep and how REM sleep fits into this overall picture is discussed elsewhere.

REM sleep is initiated by high amplitude, low frequency (1 Hertz, 1 per second) monophasic electrical spike activity known as the PGO wave (pons-geniculate-occipital). This electrical spike begins in the pons, spreading next to the lateral geniculate nucleus of the thalamus and then, finally, to the occipital cortex. PGO waves typically precede the onset of REM sleep and continue throughout this stage. They are synchronized with the lateral eye movements that occur during REM sleep.

The loss of REM sleep due to sleep deprivation is known to cause a rebound, during which the amount of time spent in this stage of sleep is increased until the loss is compensated for. This rebound phenomenon appears to be linked most closely with PGO wave activity. Following REM sleep deprivation, animals show PGO waves during stages 2 - 4 of sleep when they don't normally occur. They may even show up while the animal is awake and occur in association with bizarre behaviors suggesting that the animal is hallucinating.

In addition to dreaming, a number of other behavioral phenomena occur during REM sleep. An organism is more alert to its surroundings during REM sleep than during other stages of sleep. The incorporation of new memories from the day's events into long term memory (memory consolidation) may occur during REM sleep, and deprivation of REM sleep may impair the learning process. The amount of time spent in REM sleep may vary with intellectual ability, with retarded children spending the least amount of time and gifted children spending the most amount of time in this stage. Memory consolidation involves the development of new neuronal connections, and REM sleep is therefore associated with brain growth and development. This function appears essential to support proper development of the brain during infancy and early childhood. The elimination of unnecessary memories from the day's events may also occur during REM sleep." (REM Sleep - Inducing Areas Par 1:4)

REM sleep consists of both subjective and objective features that take affect during the course of its process in the human body. According to Diane Hales, author of "The complete book of sleep: how your nights affect your days" The subjective features involve vibration that occurs in the middle of the ear, relaxing of the muscles in the face, and limbs, and increased heart and pulse rate. Whereas the objective features involve vivid dream remembrance, and arousal, and wakefulness. The subjective and objective features provide reason to believe that REM sleep is similar to being in the state of wakefulness because the mind remains active.

The biological state of REM sleep is classified by various neurotransmitters involved in sleep and wakefulness. As explained by authors Authors: Merideth Addicott, Adrian Jaramillo and Heather Moore, of "Physiology of Sleep," three of the major neurotransmitters involved are known as acetylcholine, peribrichial, and dopamine. The cells that discharge acetylcholine are called cholinergic. The cholinergic cells project into the forebrain and cerebral cortex and hence cause stimulation of the mentioned areas resulting in behavioral arousal. Another set of neurotransmitters that plays a role in the stage of sleep and wakefulness is described as the Peribrachial area. It is thought that this area is involved in initiating REM sleep. The peribrachial neurons connect directly to brain stem regions that control eye movements, and with areas with concerned with motion, learning, and memory. Another neurotransmitter that has an important role during wakefulness is Dopamine, which originates in the cells of the substantia nigera. These cells connect with the frontal cortex, which is involved in thinking, planning, imagining,