Number of Hours Slept the Night Before

While about one in four (24%) drivers experiencing a recent drowsy driving episode reported having just four or fewer hours of sleep the night before, a full one-third (33%) of the drivers had at least seven hours of sleep. An additional 26% report receiving about six hours of sleep the prior night. [Figure 15-A]

While drowsy drivers on average had received six hours of sleep the night before they nodded off while driving, older drivers report having a drowsy driving episode even after longer sleep times. Drowsy drivers under age 30 reported an average of 5.5 hours of sleep the night before they nodded off at the wheel. The average sleep time of drowsy drivers increases with age, with those age 65 or older reporting a drowsy driving episode after an average of 7.7 hours of sleep the prior night. [Figure 15-B]

Use of Alcohol or Medications Prior to Driving

Relatively few drivers who nod off at the wheel report having had consumed alcohol (2%) or allergy or other medications (12%) prior to their trip. Alcohol is reported more of a factor among those in their 20s, of whom 5% report having consumed alcohol prior to their trip. Drivers age 30-45 are least likely to report either alcohol (0%) or medication (6%) as a factor in their drowsy driving. [Figure 15-C]