Driver sleepiness : comparisons between young and older men during a monotonous afternoon simulated drive
2014-07-30T13:39:10Z (GMT)
by
Young male drivers feature predominately in road crash statistics, especially where the driver has
fallen asleep. One possibility is that they are more vulnerable to the effects of sleep loss
compared with older men. We assessed the effect of normal night sleep versus prior sleep
restricted to 5h, in a counterbalanced design, on prolonged afternoon driving in 20 younger (av.
23y) and 20 older (av. 67y) healthy men who drove a full size, real car simulator under
monotonous ‘motorway’ conditions for 2h during the ‘afternoon dip’. Driving was monitored for
sleepiness related lane deviations, EEGs were recorded continuously and subjective ratings of
sleepiness taken every 200sec throughout the drive. Following normal sleep there were no
differences between groups for any measure. After sleep restriction, and compared with the older
group, the younger drivers showed significantly more sleepiness-related deviations, greater 4-11Hz
EEG power, and a near significant increase of subjective sleepiness. Correlations between the
EEG and subjective measures were highly significant for both groups, indicating good self-insight
into increasing sleepiness. This study confirms the greater vulnerability of younger drivers to sleep
loss under prolonged driving, even during the early afternoon.