SLEEP IS FOR THE WEAK!  Sleep-deprivation  Dependent on caffeine, especially coffee  Reaction time tests

the effect of fatigue/sleep deprivation on the reaction time of tested individuals OBSERVE AND RECORD data of caffeine - induced fatigued individuals with the sleep-deprived control COMPARE AND CONTRAST physiological concepts behind fatigue, sleep, and the effect of caffeine on the body EXPLAIN

 Volunteers were subjected to 24 hours without sleep.  Reaction tests were given at 8 th, 16 th, 20 th and 24 th hour.  Setup was repeated but this time volunteers were tasked to drink coffee (~5mg caffeine/kg body wt) mins before each test hour.  Results were tabulated and compared

 Simple tests – given one stimulus, one response is made › Record reaction time  Choice tests – one correct answer must be selected given multiple choices › Record accuracy against best score

As the number of hours without sleep increased, the reaction times with and without caffeine increased as well. Caffeine, when ingested, shortened the reaction times. For both setups, scores initially increased, peaking at the 20 th hr before rapidly decreasing. Caffeine generally resulted to higher scores.

 Fatigue & performance › Physical & mental › At the synaptic level  Depletion of transmitters in the presynapses  Progressive inactivation of many of the postsynaptic membrane receptors  Slow development of abnormal concentrations of ions inside the postsynaptic neuronal cell  Importance of Sleep › ‘restores normal levels of brain activity and normal ‘balance’ in the central nervous system functions ‘

 Caffeine › A psychoactive stimulant with the same mechanism as metamphetamines, cocaine, and heroin use in the brain › The body mistakes it for adenosine, speeding up nerve cell transmission › Influences the production of adrenaline › Increases dopamine levels in the body

 Other extraneous factors 1) Breathing cycle 2) Finger tremor 3) Vision 4) Distraction 5) Habituation to tests 6) Personality

 Fatigue decreases performance  Caffeine improves reaction times, and scores in choice reaction tests  Fatigue + Caffeine = › No amount of excitation can further stimulate a fatigued body  Don’t forget other factors References: Guyton AC and Hall JE Textbook of Medical Physiology. 9 th & 11 th eds. WB Saunders: Mansfield, PA, USA. Kosinski RJ [Internet]. A Literature Review on Reaction Time. [updated 2009 Aug 27] Clemson Univeristy; [cited 2010 Jan 30]. Available from: