Which of the following is a warning sign that a driver may be experiencing fatigue?

FATIGUE is one of the most serious safety threats in commercial trucking. The FMCSA estimates that fatigue contributes to 13% of large-truck crashes. DANGER: unlike impairment from alcohol (which a driver often feels and may attempt to compensate for), severe fatigue can cause 'microsleeps' of 4-30 seconds during which the driver is completely unconscious and the truck travels blindly. At 65 mph, a 10-second microsleep means the vehicle travels 950 feet (nearly a fifth of a mile) without any driver control. WARNING SIGNS: Head nodding or head-jerking awake; eyes closing involuntarily; drifting out of lane or hitting rumble strips; missing exits or landmarks; unable to remember the last few miles driven; yawning repeatedly; blurry vision; inability to focus on the road; restless or irritable. INCORRECT COUNTERMEASURES (work short-term, dangerously unreliable): coffee, energy drinks, turning up the radio, opening windows, slapping face. CORRECT RESPONSE: Stop at a safe location and sleep. There is no substitute for actual sleep. A 15-20 minute power nap provides real (if brief) benefit; longer sleep is better. PREVENTION: Respect hours-of-service rules even when external pressure exists to push through; maintain regular sleep schedule; avoid driving during circadian low points (2-6 AM and 2-4 PM); treat sleep disorders; don't use sleep aids that cause residual impairment.