How The Reticular Activating System Works

By Stephen Lovatt


One of the most mysterious things in the life of a human being since time immemorial is sleep. What controls it, and how do we wake up? What keeps our body functions running even when we are in the deepest form of sleep? There is no doubt that the questions are endless. The good news is that most of these questions have been answered through research. The reticular activating system (RAS) is now believed to be a significant component of the sleep wake cycle.

Scientists first encountered the RAS in 1949 and what we know today has its basis on this breakthrough discovery. It was established that the system is made up of multiple nuclei located in the brain stem and the thalamus. The name comes about because of the presence of numerous fibres that interconnect these fibres forming a reticular pattern. If the fibres are damaged for one reason or another, there will be disorders in sleep.

A number of chemicals modulate the connections that exist in the system. They are termed neurotransmitters and are broadly classified into cholinergic and adrenergic. Based on the intended physiological response, these chemicals may work synergistically or competitively. A chemical called glutamate is the main cholinergic type that is involved in this process while adrenaline is the main adrenergic type. In general, an increase in the level of neurotransmitters causes increased alertness.

The mediation of sleep wake transition is undoubtedly the main function of RAS. There is a varying degree of activation depending on the depth of sleep; the deeper the sleep, the more the activation and the lighter the sleep, the less the activation. Another function is that of initiating and maintaining a state of alertness and attention whenever there is such a need. Increased blood flow to the thalamus and the midbrain during these events is evidence of this.

RAS is very important to survival. It helps in instructing the rest of the brain on what is important and what is not at any given point in time. This is very significant considering that we are faced with tons of information in our environment. These come in the form of stimuli that may be auditory, visual, tactile or gustatory. There is need to filter these and leave out the irrelevant.

A number of factors have been shown to hinder the development of this system. Preterm birth is a risk factor to a compromised RAS. A significant number of children born before their time have problems remaining alert and awake for a long period in their development. Smoking during pregnancy has also been shown to be a risk factor and is said to abnormally increase arousal.

A number of diseases that affect the central nervous system are said to bear some relationship to a disorder of RAS. These are mainly the result of a slowing down of RAS activity which may happen with advancing age. Consequently there is a higher incidence of these diseases in the elderly compared to the general population. Examples include narcolepsy, posttraumatic stress disorder, attention deficit disorder and schizophrenia.

Good leaders need to take care of their RAS. To achieve this, there is a need to have thought training regularly. One way in which this ca be achieved is to ensure that you take care of your personal issues promptly. This ensures that you are not constantly distracted. Setting of goals is also important.




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