Chapter 2 - Frequently Asked Questions

  1. Why so much emphasis on mental fatigue? Isn't physical fatigue equally important? 

    Physical fatigue can impair physiological and psychological performance in a similar way to mental fatigue. However, unlike mental fatigue, physical fatigue can be managed with rules governing hours of service. Mental fatigue, on the other hand, is more complex and needs attention on many different levels. Using a systems-based approach to managing mental fatigue will also manage physical fatigue. 
  2. Is it true that older people need less sleep than younger people? 

    It is true that older people get less sleep than younger people. However, there is no evidence that they need less sleep. As we age, it is common for our sleep patterns to change. While the overall amount of sleep we get remains roughly the same, older people tend to wake more often during the night and get their sleep in shorter blocks. Age also brings hormonal changes that affect the type of sleep we get – older people experience less REM (dreaming) sleep than younger people. This is one of the reasons that adapting to shiftwork becomes more difficult as we get older. 
  3. How do you determine whether fatigue is a factor in accidents?
    In accident statistics, fatigue is generally inferred from the time of day that the incident took place (midnight to 6 a.m.). Single vehicle accidents in which suicide has been ruled out are also included. Other factors that are considered include time on task (greater than 9 hours) and the work schedule of the previous seven days. You can see that this is not very exact – the contribution of fatigue to accidents is probably underreported. 
  4. When you look at the graph showing performance after being awake for a long time (Slide 12), why does performance start to go back up after being awake for 24 hours? 

    This is a demonstration of the effect of the body's circadian rhythm. When the sun rises, our body “resets” (to a degree), and performance improves as the body naturally wakens and becomes active. Many people call it getting a second wind. However, it’s not likely that performance will reach the same level as the previous day. 
  5. Can performance testing be used in the workplace as a check of fitness for duty?
    Some workplaces may use performance tests for exactly that. However, there are a number of limitations. First, every employee must be tested against his or her own baseline (when they are not fatigued). Second, performance testing requires a lot of data management, and supervisors and employees need feedback right away. Third, it is difficult to draw a line at which an employee is “unfit for duty” based on the test. Tests can be used as a tool to determine how often and under what conditions employee performance is worse than normal. 
  6. Isn't an FRMS just dictating to employees what they do in their time away from work?
    An FRMS is not about controlling employees’ lives, but it is about setting an expectation that they arrive at work fit for duty. This includes managing their time away from work to ensure they receive adequate rest and sleep. If, for whatever reason, employees aren’t able to get enough rest, it is their responsibility to report it as a potential risk. It’s no different from rules about the number of hours you must wait between drinking alcohol and starting work.
  7. You say individuals need 5-6 hours sleep to sustain appropriate levels of performance. What if an employee maintains he or she only requires 2 hours sleep a night, and feels perfectly fine?

    Research has found that most people need 5-6 hours sleep. A small percentage of people can get by on less. More often what happens is that people get used to functioning on less sleep. Their standard of feeling wide awake and alert drops, and they get used to living and performing at a lower level of alertness. It becomes normal. When these same people take a long holiday, they usually sleep a lot more than 5 hours and feel a lot more alert. If you consistently report getting less than 5 hours’ sleep, but don't display any fatigue-related symptoms, you're not likely to be a significant risk to the organization. However, conduct an experiment and try to get 6-8 hours sleep for a couple of weeks. If you feel a positive difference in your level of alertness, you should aim to get this much sleep on a more regular basis. On the other hand, if you still feel you can get by on less than 5 hours of sleep, you should consider seeing a doctor to find out whether your performance is really as good as it could be, or whether you may have a sleeping disorder.
  8. How do I know if I have a sleep deficit?
    Besides feeling tired all the time, one of the major signs of sleep deficit is sleep latency – how long it takes you to fall asleep. A normal sleep latency is approximately 15 minutes. If you need a lot less to fall asleep, it may mean that you have a sleep deficit – particularly if you fall asleep within one or two minutes, or find yourself falling asleep unintentionally. If you take a lot longer to fall asleep, you may be suffering from insomnia.
  9. Is there an ideal length for a nap?
    If you are really fighting sleep, and are trying to perform a job that involves any level of risk (e.g., driving, engine overhaul, refuelling), any nap is better than no nap. Research has found that naps as short as 10 minutes can be effective in increasing alertness. The longer the nap, the longer the benefits will last. However, longer naps are also associated with longer periods of sleep inertia (that groggy feeling when you wake up) afterward. When napping is permitted in the workplace, it should be limited to about 40 minutes.
  10. Caffeine doesn't seem to affect me at all – in fact, if I don't have a coffee before bed, I wake up with a headache. Why is that?
    Caffeine is only effective when used strategically. People who regularly drink caffeine will not get the same level of stimulation as people who only drink caffeine when they are tired and need a kick. Caffeine is addictive. Regular caffeine drinkers who suddenly stop often experience headaches, dizziness, and/or nausea. If you wake up with a headache if you don’t have a coffee before bed, it may mean that your body is over-dependent on caffeine.
  11. I find that rolling down the window or listening to the radio or chewing gum helps me to stay awake when driving home. How effective are these strategies for reducing the risk of a fatigue-related accident?
    Contrary to popular opinion, these techniques for staying alert while driving are not enough to safeguard you against falling asleep at the wheel or causing an accident. Driving fatigued impairs your performance in a similar way that driving drunk does. Even if you think you’re okay, bear in mind that sleep can come when you’re not expecting it. You are not always able to accurately judge just how sleepy you really are.
  12. Why do we need to sleep?
    Scientists don’t know the exact reason we need to sleep, although it is clearly necessary to allow the body to recover from the stresses of the day. Humans that have suffered prolonged sleep deprivation experienced symptoms such as hand tremors, slurred speech, increased sensitivity to pain, and reduced mental and physical performance. 
  13. When is the human body most susceptible to the effects of fatigue? 
    The lowest point in the circadian rhythms that affect the body’s alertness is between 2 a.m. and 6 a.m. If you wake from a nap in this period, remember that you’re likely to experience long sleep inertia. If you’re awake during these times, your alertness may be affected. 
  14. Why is fatigue receiving so much attention now, when it has never been an issue in the past?

    First, our understanding about the risks associated with fatigue has evolved a lot in recent years. And as more and more people take up shiftwork and other alternative working arrangements, the potential for fatigue-related accidents increases. This risk is made worse by the increasing use of high-powered machinery, where the margin for error is lower and the consequences of accidents potentially very serious.
  15. Would you encourage the use of sleeping pills as an aid to getting enough sleep in time away from work?
    If you cannot sleep at all, or have a lot of difficulty getting to sleep, sleeping pills can be an effective strategy to retrain your body to sleep. However, you shouldn’t use them over the long term. You can develop a dependency on sleeping pills after just one week. Long-term use of sleeping pills can cause irritability, headaches, nausea, depression, muscle loss, and increased appetite. You should use them only for short periods.
  16. Does shiftwork have any impact upon pregnancy?
    Although the effects of shiftwork on pregnancy are slight (only marginally higher than for day workers), there are some effects that are worth being aware of. Some types of shiftwork have been linked to increased time to conception, increased risk of premature birth, lower rates of fetal growth, and increased risk of miscarriage. Although these risks are slight, you may wish to discuss them with your doctor.
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