Remember those all-nighters you pulled back in school? Remember how good you felt afterwards? Most of us did not feel all that good after only a few hours of sleep. And fatigued? Oh yes, tremendously. There was just enough energy to hand in the paper or write the exam and get back home to bed. With this little amount of sleep, connecting it to fatigue is not difficult. Most of the time, you were so fatigued that you were asleep before your head hit the pillow.
Although the all-nighters might have ended, burning the candle at both ends, so to speak, by juggling work demands, family and personal responsibilities can also reduce the amount of sleep you get. So just how much sleep should you be getting? Most research shows that people need between 7 and 8 hours[1] of good quality, uninterrupted, night time sleep to function well and keep fatigue at bay. But some people need as little as 6, and some people need as much as 9 consecutive hours of sleep. Regularly sleeping outside this 6 to 9 hour range is very unusual[1].
In the transportation realm, tight turn arounds, split shifts, personal responsibilities and sleeping during the day can make getting enough ZZZZ’s difficult; especially for people who are cutting their sleep time down to their bare minimum. For someone who regularly needs 7.5 hours of sleep, reducing it by as little as 2 hours for one night can significantly increase their risk of fatigue the next day.
I investigated an aviation accident[2] for the Transportation Safety Board of Canada where this exact thing happened. In this occurrence, a Cessna Caravan took off in overweight and icing conditions and then crashed into Lake Erie’s frozen surface, killing all 10 people on board. The pilot squeezed in a personal visit to Los Angeles before returning to work in Toronto early the following morning. We figured that the pilot cut his sleep back by about 2.25 hours (to 5.25 hours) from his normal amount for the the LA excursion. We concluded that stress combined with fatigue, resulting from sleep loss, likely affected the pilot’s decision making and led to taking off overweight and with icing on a wing.
References
[1] See for example: Anch, A., Browman, C., Mitler, M., & Walsh, J. (1988). Sleep: A Scientific Perspective. New Jersey: Prentice-Hall.
[2] Aviation Investigation Report, A04H0001, Loss of Control, Georgian Express Ltd., Cessna 208B Caravan, C-FAGA, Pelee Island, Ontario, 17 January 2004.