A microsleep is a short period of time, usually between 10 seconds to a minute in length, in which the brain actually enters a sleep state, regardless of what the person is doing at the time. The affected individual often does not know that this momentary blackout has occurred. The effects of these microsleeps combined with attentional lapses, however, can be dramatic.
There is now evidence that many major disasters have been due to sleep-debt related effects. The evidence shows that these include the oil spill of the Exxon Valdez, the nuclear accidents at Chernobyl and Three Mile Island, and the loss of the space shuttle Challenger (Coren, 1996a).
In fact, our societal sleep debt is so great that simply losing one additional hour of sleep due to the spring shift to daylight savings time can increase traffic accident rates by 7% (Coren, 1996b) and death rates due to all accidents by 6.5% (Coren, 1996c).
When sleep deprivation becomes great enough, the effects mimic those of psychosis. The failure of the scientific world to recognize this is due to some extent to the folklore that has grown up around the sleepless marathon of high school student Randy Gardner in 1964.
To gain an entry into the Guiness Book of World Records, he remained awake for 264 hours (11 days). Summaries of this case usually report that Gardner suffered no hallucinations, no paranoia or other negative mood changes, and that his mental, motor and sensory abilities were quite good throughout the entire episode. This conclusion is so widespread that it has now become a stock "fact" presented in virtually any psychology or psychiatry book that has a chapter on sleep.
This conclusion seems to be based on two items of information. The first was the observation that there were no obvious lasting physical or mental problems encountered by Gardner when he began to sleep again. The second was based upon observations of researcher William Dement (Dement, 1992), who interviewed Gardner on Day 10 of the experiment. He reported that he took Gardner to a restaurant and then played pinball with him, noting that Gardner played the game well and even won. Lt. Cmdr. John J. Ross of the U.S. Navy Medical Neuropsychiatric Research Unit in San Diego, who was called in by Gardner's worried parents to monitor his condition, tells a quite different story (Ross, 1965). Gardner's symptoms that Ross reported included:
- Day 2: Difficulty focusing eyes and signs of astereognosis (difficulty recognizing objects only by touch).
- Day 3: Moodiness, some signs of ataxia (inability to repeat simple tongue twisters).
- Day 4: Irritability and uncooperative attitude, memory lapses and difficulty concentrating. Gardner's first hallucination was that a street sign was a person, followed by a delusional episode in which he imagined that he was a famous black football player.
- Day 5: More hallucinations (e.g., seeing a path extending from the room in front of him down through a quiet forest). These were sometimes described as "hypnagogic reveries" since Gardner recognized, at least after a short while, that the visions were illusionary in nature.
- Day 6: Speech slowing and difficulty naming common objects.
- Day 7 and 8: Irritability, speech slurring and increased memory lapses.
- Day 9: Episodes of fragmented thinking; frequently beginning, but not finishing, his sentences.
- Day 10: Paranoia focused on a radio show host who Gardner felt was trying to make him appear foolish because he ws having difficulty remembering some details about his vigil.
- Day 11: Expressionless appearance, speech slurred and without intonation; had to be encouraged to talk to get him to respond at all. His attention span was very short and his mental abilities were diminished. In a serial sevens test, where the respondent starts with the number 100 and proceeds downward by subtracting seven each time, Gardner got back to 65 (only five subtractions) and then stopped. When asked why he had stopped he claimed that he couldn't remember what he was supposed to be doing.
In many respects Gardner's symptoms were similar to those experienced by a New York disk jockey, Peter Tripp, who endured a 200-hour sleepless marathon to raise money for the March of Dimes. During the course of his ordeal his thoughts became increasingly distorted and there were marked periods of irrationality. By the end of four days he could not successfully execute simple tests requiring focused attention. In addition, he began to have hallucinations and distorted visual perceptions. At one point Tripp became quite upset when he thought that the spots on a table were insects. He thought that there were spiders crawling around the booth and even once complained that they had spun cobwebs on his shoes.
Coren S (1996a), Sleep Thieves. New York: Free Press.
Coren S (1996b), Daylight savings time and traffic accidents. New Eng J Med 334:924.
Coren S (1996c), Accidental death and the shift to daylight savings time. Percept Mot Skills 83:921-922.
Dement WC (1992), The Sleepwatchers. Stanford, Calif.: Stanford Alumni Association.
Palinkas LA, Suedfeld P, Steel GD (1995), Psychological functioning among members of a small polar expedition. Avia Space Environ Med 66:943-950.
Ross JJ (1965), Neurological findings after prolonged sleep deprivation. Arch Neurol 12:399-403.
Webb WB, Agnew HW (1975), Are we chronically sleep deprived? Bull the Psychonomic Soc 6:47-48.