No doubt you think you’re an excellent driver. You may very well be. But that doesn’t mean that you’re always at peak performance when you sit behind the wheel and get out on the road. In fact, if you’re attempting to drive after missing a night’s sleep, you could be a danger to yourself and others.
This isn’t a statement designed to rile you up. Instead, it’s based on scientific expert consensus from the Drowsy Driving Consensus Panel published in the June 2016 online edition of Sleep Health, the official journal of the National Sleep Foundation.
The conclusion of the Drowsy Driving Consensus Panel is that if you’ve slept less than two hours during the last 24-hour period, you are too sleep-deprived to get behind the wheel of a vehicle. But there’s more to the story. Here are some of the specifics that deserve attention.
Prevalence and Effects of Sleep Impairment
If you have experienced the fogginess that occurs after a poor night’s sleep, you’re not alone. More than one in four Americans report they get less than enough sleep on most nights. Only one in three say they consistently get the right amount of sleep.
- Insufficient sleep impairs neurobehavioral performance that reduces a driver’s ability to operate a car in a safe manner.
- Drowsy drivers have diminished neurocognitive performance across all the key areas related to the task of driving:
- Delayed reaction time
- Impairment in visual perceptive ability
- Increased distractibility
- Reduction in the ability to focus attention
- Memory impairment
- Increased likelihood of eyelid closure and risk of loss of situational awareness – even when the eyes are open
- Slowed cognitive processing
- Deteriorating vigilance with time-on-task
- Sleep loss impairment is comparable to alcohol intoxication. Being awake for 24 hours results in neurobehavioral performance impairment similar to being intoxicated to a level of .10 Blood Alcohol Concentration (BAC).
- Just as with the effects of alcohol, lack of sufficient sleep negatively affects judgment and decision-making ability. Sleepy drivers underestimate how much lack of sleep has on their performance, with the result that they often become “fast and sloppy” (increase their speed at the expense of making more mistakes) and wind up taking greater risks.
Insufficient Sleep Duration Vs. Other Factors
Although the project focused on sleep duration over the past 24 hours as an identifiable target to reduce the number of excessively sleepy drivers on the road, there are several other factors that also contribute to sleep-related driving performance. The conclusion that drivers with only two hours of sleep are unfit to drive serves as a threshold. The panel also concluded that most healthy drivers would be impaired with three to five hours of sleep during the previous 24 hours.
Other factors also contribute to sleep-impaired driving, such as:
- Quality of sleep
- Wakefulness duration
- Psychological need for sleep
- Cumulative sleep debt
- Biological time of day (i.e., circadian clock)
- Recency of last sleep episode
- Physical activity level
- Time on task
- Light exposure
- Use of stimulant or hypnotic substances
- Sleep disorders
- Other medical and/or psychiatric conditions
Among the 50 to 70 million Americans estimated to suffer with a sleep disorder, most remain undiagnosed and untreated. That contributes greatly to the numbers of drowsy drivers on the road at any given time.
Medication side effects, working non-traditional schedules, and situational factors such as driving for extended periods, driving at night and driving long distances also contribute to an increased risk for sleep-related car crashes.
The full article, “Sleep-deprived motor vehicle operators are unfit to drive: a multidisciplinary expert consensus statement on drowsy driving Sleep Health (2016)” by Czeisler CA, et al., is available at file://dx.doi.org/10.1016/j.sleh.2016.04.003.
The National Sleep Foundation has some tips on how to get a good night’s sleep. Among them are the recommendation to have a dark, quiet and comfortable environment to sleep in, stick to regular sleep and waking up times, and make use of a relaxing bedtime routine.
Other practical tips include adding regular vigorous exercise to your day, sleeping on a comfortable mattress and pillow, avoiding naps during the day, don’t drink, smoke or eat heavy meals late in the day, using the last hour of the day to wind down and, if all else fails and you can’t get to sleep, go into another room and do something else until you feel tired.
Persistent insomnia may require a trip to the doctor for a medical checkup. Often, the root cause is something that can be treated.
Another helpful practice is to keep a sleep journal or diary. This is simply recording the habits and practices you notice that may be contributing factors to your poor sleep results. Once you identify things you’re doing that have a negative effect on your night’s sleep – like wolfing down that gigantic slice of cake and then heading off to bed, drinking coffee late in the evening, engaging in activity that’s too stimulating in the hour before you go to bed – you can do something about it to change your routine.
It’s worth noting that everyone has problems getting to sleep and staying asleep now and then. If it happens only rarely, you probably won’t have a problem – just don’t drive after only two hours of sleep. If you experience regular sleeplessness, getting up too frequently in the night and being unable to get sustained, quality REM sleep, you’ll need more help to reverse this pattern. And definitely don’t get behind the wheel and attempt to drive until you do.