Short sleep duration, snoring and subjective sleep insufficiency are independent factors associated with both falling asleep and feeling sleepiness while driving.
Level 4 - case-series / case-control
Cross-sectional questionnaire-based survey
PubMed 23207120 · doi:10.2169/internalmedicine.51.7518
What was done
A questionnaire-based cross-sectional survey evaluated 4,097 experienced drivers visiting a driver licensing center in Tokyo. Researchers analyzed associations between socio-demographic factors, sleep variables (sleep duration, witnessed loud snoring or apnea, subjective nocturnal sleep insufficiency), and self-reported experiences of feeling sleepy or falling asleep while driving using logistic regression.
What was found
Of the 4,097 drivers, 11.4% experienced at least one episode of falling asleep while driving in the prior year, and 67.6% had experienced feeling sleepiness while driving. Witnessed snoring/apnea, short sleep duration, and subjective sleep insufficiency were each independently associated with both outcomes. Sleep duration less than six hours was associated with subjective sleepiness while driving, whereas falling asleep while driving was associated with a sleep duration of less than seven hours (odds ratios and confidence intervals were not reported in the abstract).
Why it matters
Sleeping fewer than seven hours may increase the risk of falling asleep while driving even in the absence of perceived sleepiness, underscoring the inadequacy of relying solely on subjective fatigue before driving.
Limits
The cross-sectional design precludes establishing temporal causality. All measures, including sleep duration, witnessed apnea, and driving incidents, relied on self-reported questionnaires without objective validation (such as polysomnography or driving telemetry), creating potential for recall and social desirability biases.
Cited by
- context Drivers who obtain only 5 or 6 hours of sleep are three times more likely to nod off behind the wheel, even if they report feeling fully well-rested.