Patricia Sagaspe, PhD, of the Clinique du Sommeil at CHU Pellegrin in Bordeau, France, studied 24 people, 12 young (between 20-25 years of age) and 12 middle-aged (between 40-50 years of age). Participants first drove 125 highway miles in the daylight, between 6:00 and 7:30 p.m. Then, in a test of the effects of coffee and napping on night-time driving, participants drove another 125 miles between 2:00 and 3:30 a.m. after having a cup of coffee with 200 mg of caffeine, a placebo (a cup of decaffeinated coffee with 15 mg of caffeine) or a 30-minute nap.
Inappropriate line crossings, self-perceived fatigue and sleepiness and polysomnographic recordings were analyzed in the study. According to the results, compared to daytime, after a placebo, the number of inappropriate line crossings was significantly increased. Compared with a placebo, both coffee and napping reduced the risk of inappropriate line crossings in young and middle-aged participants. A significant interaction between age and condition showed that napping led to fewer inappropriate line crossings in younger than in middle-aged participants. During napping, young participants slept more and had more delta sleep than middle-aged participants.
Self-perceived sleepiness and fatigue did not differ between age groups, but coffee improved sleepiness, whereas napping did not.
„The potential effect of age on response to sleepiness countermeasures should be considered in populations exposed to extended wakefulness,“ said Dr. Sagaspe. „According to their age or individual physiology, subjects should implement their best countermeasures to sleepiness at the wheel.“
MEDICA.de; Source: American Academy of Sleep Medicine