Sleep, Circadian Rhythms

Sleep is a natural state of reduced consciousness involving changes in body and brain physiology which is necessary to man to restore and replenish the body and brain.
Five stages of sleep:
  1. Stage 1: Transitional phase between waking and sleeping. Heart rate slows and muscles relax. It is easy to wake someone up.
  2. Stage 2:  deeper level of sleep, but it is still fairly easy to wake someone.
  3. Stage 3: Sleep is even deeper and the sleeper is now quite unresponsive to external stimuli and so is difficult to wake. Heart rate, blood pressure and body temp continue to drop.
  4. Stage 4:  deepest stage of sleep and it is very difficult to wake someone up.
  5. REM Sleep:  the person is even more difficult to awaken than stage 4. Brain is active. It is also known as paradoxical sleep. Muscles become totally relaxed and the eyes rapidly dart back and forth under the eyelids.  dreaming occurs during REM sleep.
Stages 1 to 4 are  known as Non-REM Sleep. NREM
Stages 2 to 4 are slow-wave sleep and appear to relate to body restoration, 
REM sleep seems to aid the strengthening and organisation of memories. 
Sleep deprivation if a person is deprived of stage 1-4 sleep or REM sleep he will show rebound effects.
        This means that in subsequent sleep, he will make up the deficit in that particular type of sleep. This shows the importance of both types of sleep.
Sleep occurs in cycles. REM sleep will occur about 90 minutes after the onset of sleep. The cycle of stage 1 to 4 sleep and REM sleep repeats during the night about every 90 minutes. Most deep sleep occurs earlier in the night and REM sleep becomes greater as the night goes on.
Circadian rhythms are physiological and behavioural functions and processes in the body
that have a regular cycle of approximately a day (actually about 25 hours in man).

Popular posts from this blog

Human Factor Introduction

Human Factor -  A  Person working in a maintenance environment requires human factor knowledge as per his job requirement. Human Factor Training  - Aviation safety relies on maintenance. When it is not done correctly , it may cause an incident or an accident.  Mistakes of maintenance personnel is difficult to detect. They are subjected to work in changing working in variety of adverse conditon. Regulatory Requirement : CAR 66 Module 09 Human factor - for get AMEL Human Factor   - Study of human capabilities and limitations in the workplace.   It is about study of the interaction  of maintenance personnel, the equipment used, the written and verbal procedures and  rules followed by them, and the environmental conditions of any system.  Aim of human  factors is to optimise the relationship between maintenance personnel and systems to improve  safety, efficiency, and well-being. HF - Fitting the man to the job and the job to th...
Read more

SHEL(L) Model

Model are used to understand human factor  as a framework around which human factor issues can be structured. SHEL(L),PEAR, Dirty Dozen  S - Software H - Hardware L - Liveware E - Environment                                         Liveware  is at the center of the model, is   the most critical and flexible component in the working  Environment and subject to considerable variations in performance and suffer many limitations.                           Physical size and shape.  In the design of workplace and equipment, body measurements and movements is considerd , which may vary according to factors such as age, ethnicity and gender. Human Factors inputs is provided  in the design process, and data for these inputs are available from anthropometry, biomechanics and k...
Read more

Information Processing Limitation

Human information processing  have limitations.   AMT requires support such as reference  to written material (e.g. manuals). Attention and Perception -  A proportion of ‘sensed’ data may be lost without being                              ‘perceived’.   Failing to  perceive  something  which   someone  has said to you, when you are concentrating on something else, even  though the words would have been received at the ear without any problem.  Information processing system has  ability  to perceive   something (such as a picture,                       sentence, concept, etc.) even though some of the data  may be missing.  Danger - people can fill in the gaps with  information from their own store of knowledge or experience, and this may lead to  t...
Read more