It is fact that many of us are not getting enough sleep.
In his October column, Garth Wallace described a pilot who fell asleep with the auto pilot on. That may be extreme, but how many of us at the end of a long day while winging our way home cannot remember a short portion of the flight. We might have had a micro sleep and didn’t know it.
The official definition of fatigue is "Performance impairment arising from loss of sleep and/circadian disruption."
Fatigue can be either acute or chronic, Acute fatigue is of short duration. One or two bad nights are an example. We know we are tired and we normally act accordingly. One or two good night’s sleep will repair the damage.
Many of us though suffer from chronic fatigue. Recent studies have again showed that 90 per cent of us need about 7.5 to 8.5 hours of sleep per night. Many of us have gotten by on less for years. The problem is, we have a tendency to underestimate the amount of sleep we actually need and we over estimate our ability to cope with the lack of sleep.
Every hour of sleep we lose accumulates as sleep debt. If we short ourselves an hour a night Monday through Friday, we have accumulated five hours of sleep debt. A weekend is not enough to settle that debt. Many of us carry this through for weeks on end.
One U.S. study showed their test subjects lost on average one point of their IQ for each hour of accumulated sleep debt. That would make some of us walking idiots.
The only antidote for chronic fatigue is more sleep. We need to sleep longer each night over an extended period to erase the sleep debt, and to keep from starting another sleep debt cycle.
We often feel we are making up for a late Saturday night by sleeping late Sunday morning. The problem is if we do that, we are not really ready for sleep at our normal time on Sunday night. We don’t sleep well and we tend to perform poorly on Monday.
Shift workers often suffer from chronic fatigue. It takes about two weeks for a body to adjust to a new schedule that is eight or more hours different from one we are used to. Our circadian rhythm of natural alertness and sleepiness is disrupted.
Most shift workers don’t remain on a schedule for that long. On the first night of a night shift most workers can expect to have their performance affected as much as it would be at a blood alcohol level of .1 per cent. I hope they are not working on my airplane.
Each spring and fall we change our clocks ahead or back just one hour. Provincial and private auto insurers note a significantly increased accident rate each time, proving that even minor changes in our sleep schedules reduce our alertness.
Just being awake for an extended period affects our performance. After being awake for 17 hours we can expect to exhibit the same performance as we would with a blood alcohol level of .05 per cent. We should think about this if we are planning a night flight after working a full day.
Many factors affect our sleep. Some are medical, such as sleep apnea (temporarily ceasing to breathe). Medical factors can usually be corrected. We should take our wife’s advice and see a doctor. Maybe she can then get some sleep as well. Yeah, guys suffer from such maladies more frequently than women and we seek help less often.
Other factors that affect our sleep are stress, pressure and nutrition. We are all affected by these to a degree. The key is to recognize that we are affected by stress or pressure. If we don’t recognize it, we can’t deal with it.
Again, most of us tend to underestimate the affect stress or pressure has on us and over estimate our ability to deal with it.
We also frequently tend not to eat as well as we should. We make sure our aircraft is fuelled. Why not our bodies? The combination of stress and poor nutrition has a significant effect on us. We do not sleep as well and the stress uses up energy. Poor nutrition doesn’t replenish that energy. We start fatigued and become more fatigued easily.
EFFECTS OF FATIGUE ARE:
TO AVOID FATIGUE:
IF YOU ARE TIRED:
The full role of sleep is still not fully understood. We do know that breathing, heart rate and blood pressure all drop during sleep. Something serious is going on.
We all hear about pilot error being the cause of most accidents. We seldom discover why the pilot made the errors in judgement he or she made. I would wager that fatigue was a factor in many of them.
Sleep well, fly safely.
Dale Nielsen is an ex-Armed Forces pilot and aerial photography pilot. He lives in Abbotsford, B.C., and currently flies air charters. He still freelances as a flying instructor and seminar facilitator. Nielsen is also the author of seven flight training manuals published by Canuck West Holdings.
Got an aviation safety story to tell? Dale Nielsen would like to hear from pilots who have educational aviation experiences to relate. Excerpts from these stories will be used in upcoming safety articles. Dale can be contacted via e-mail: firstname.lastname@example.org
Note: Much of the information in this column was taken from TP 13459-1E "Human Performance in Aviation Maintenance Workshop"