The principle of these tests is that patients who are sleepy have a reduced ability to maintain attention. Their main value is in assessing responses to treatment by serial testing. Repetitive and unpredictable stimuli, such as flashing lights, are presented to the subject who has to respond as rapidly as possible. Delays or failure to respond to these stimuli are recorded. These tests require the subject's cooperation and are influenced by the degree of motivation. Reaction times are longest between 2.00 and 4.00 pm when there is an increased circadian tendency towards sleepiness.
The psychomotor vigilance test (PVT) scores the number of lapses and long response times. The normal value is 250-350 msccs, but if the subject is sleepy the number of longer response times increases as the subject attempts to maintain accuracy . Lapses are more frequent, but the results depend not only on vigilance but also on experience with the test and coping strategies.
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Salvation For The Sleep Deprived The Ultimate Guide To Sleeping, Napping, Resting And Restoring Your Energy. Of the many things that we do just instinctively and do not give much of a thought to, sleep is probably the most prominent one. Most of us sleep only because we have to. We sleep because we cannot stay awake all 24 hours in the day.