Defining the problem. To reduce fatal crashes between trucks and other vehicles, a study was conducted to identify when most of the fatalities are occurring and under what circumstances. . Who’s at “ FAULT ” in fatal accidents involving trucks & other vehicles. OTHER DRIVER AT FAULT = 71%
In two-vehicle fatal crashes between large trucks and passenger cars,
A significant number of vehicle accidents are caused by
Operator fatigue, is a state of mind and body, a response to continued physical or mental activity or sleep loss, is characterized by diminished ability to work, loss of attention, slower reactions, poor response, deterioration of attention or alertness, & impaired judgment.
Fatigue can be caused by combinations of inadequate rest, sleep loss and/or disrupted sleep, displaced biological (circadian) rhythms, excessive physical activity or mental work, and general psychological stress.
… a temporary loss of muscle power to respond to demands
…a feeling of tiredness, soreness, or discomfort
…physical performance declines
… a feeling of tiredness after extended or repeated tasks… particularly non-physical tasks such as driving
…may include feeling of monotony or boredom caused by lack of varied stimulation.
… negatively affects your level of alertness at the wheel & leads to poor driving performance
… a short term condition that can be relieved by adequate rest and sleep; usually we can recover full alertness in just a few days with longer sleep (Sleeping longer on weekends, etc.).
… results from repeated and cumulative stress… some refer to it as “Burnout”
…may require extended break… several days off
….Quality & quantity of rest or sleep
….Individual physical fitness
….Individual endurance to demanding tasks
….Environmental conditions of heat, humidity, cold, altitude, etc.
….Performance on sustained work suffers before that on intermittent tasks
Types of Tasks, Time-of-Day, Personal Motivation & Individual Differences
Sleep requirements differ for individual persons, and vary with age (infants, adolescents, young adults, mid-aged adults, seniors).
Most adults maintain normal alertness, perform near their best, by obtaining 7- 8 hours of uninterrupted sleep every 24 hours.
Some people get by with less sleep (5-6 hours) but often augment this sleep with naps.
Others think they can get by with less sleep, but in reality, if their performance were measured it is degraded.
Normal nighttime sleep involves 4-5 repeated 90 minute cycles of brain electrical activity (coded into 5 sleep stages) as we restore ourselves to a refreshed, alert state, or we recuperate from sleep loss and fatigue.
Rapid eye movement (REM) or dream sleep and slow wave sleep (stages 3 & 4 are deep sleep) seem to be the most recuperative.
A period of 4+ contiguous hours of sleep permits several uninterrupted 90-minute cycles.
Eight 1-hr sleeps are not the equivalent to a full 8-hrs of sleep. Intermittent, broken sleep is usually detrimental to alertness.
When we miss sleep required to maintain normal alertness, we accrue a “SLEEP DEBT” which accumulates each successive 24-hr day we shortchange ourselves of anticipated sleep (obtaining only 5 hrs one night minus our required 8 nets 3-hr sleep debt).
If after several days our sleep debt accrues to 10-12 hrs sleep debt (more than one night’s sleep loss) we begin to perform as if we missed an entire night’s sleep.
Paying off a sleep debt usually does not require a 1-for-1 replacement of hours missed sleep.
A “tired” brain quickly goes into a sleep stages 3 &4 which makes efficient use of the first long duration sleep period
Consequently, we spend a shorter time in the less restorative sleep stages (1 & 2), but more time in states 3, 4 and REM sleep
After weekly sleep debt of 15+ hrs we might make up a debt with one or two long duration recovery sleeps (10+ hrs) on the weekend.
Rest may be a break in activity, or simply a change of pace or even a change in activities.
Rest breaks permit us to restore our energy, break the monotony, or give our bodies and minds relief.
Frequent Rest Breaks Can Be Helpful in Any Sustained Work.
But Rest Is Not the Same As Sleep,
And It Will Not Substitute for Needed Sleep.
… our physiological & behavior patterns repeat daily in synchronization with our internal biological clock.
…body core temperature, urine production, hormonal excretions, digestive processes etc…. Repeat at the same time each day.
…as we wake up from a night’s sleep, our body temperature begins increasing, and gradually rises through the day until about 1 to 3 PM when it levels off somewhat.
… being awake past mid-night after no sleep results in feeling groggy, less alert, and performance is considerably degraded in this circadian low period (midnight to 4 AM) when our brain would prefer to be asleep.
…best time to obtain sleep is during the C-R lows (afternoon siestas or naps are valuable).
…if you cannot sleep during the C-R lows, taking a rest break will be beneficial
…sleeping, working, and eating meals on a new schedule requires a period of from one to three weeks for the body to adjust to the new rhythm, a period during which the worker is likely to experience “Shift- Lag” much like trans-meridian travelers experience “Jet Lag”.
… forward shift rotations are easier than backward rotations.
… as an example, it is generally easier to adjust to flying westward by staying awake longer that day.
…sleepiness and fatigue can be a serious threat to safe vehicle operation.
…fatigue is physiological and can be can be affected by our psychological factors.
… plan ahead to get enough sleep
… be aware of the “brain & body” principles of fatigue and sleep loss
…plan ahead, both at home, and on long trips,
…implement fatigue countermeasures