Coffee is an effective countermeasure to sleepiness for both young and middle-aged people.
However, napping is more efficient in young than in middle-aged people, according to a study published in the December 1 issue of the journal SLEEP.
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.