Sleepiness during night-shift - sleeping habits or melatonin rhythm? A laboratory study

摘要

This study examined the relation between individual sleeping habits, and sensitivity to sleepiness during five simulated night-shifts. Seventeen male volunteers were selected by their features of "morningness-eveningness" and flexibility or rigidity of sleeping habits. Subjective scales of sleepiness and fatigue, mental performance, sleep, attenuation alpha test and the melatonin circadian rhythm were measured. Data analysis compared the following groups: evening-morning, flexible-rigid, evening-flexible, morning-flexible and morning-rigid groups, and two other definite groups from the total sample: a first group with an advanced onset of melatonin production at 23:00 and a second group (delayed onset) at 02:00. Results showed that morning, morning-flexible, morning-rigid and advance groups presented more adjustment difficulties than evening, evening-flexible and delay groups. Differences between flexible and rigid subjects remained less pronounced because of the heterogeneity of samples. The results of this preliminary study suggest that melatonin production and a combination of the two dimensions "eveningness" and "flexibility" of sleeping habits could explain the capacity to adjust to night-work.