Differences in cardiovascular and central nervous system responses to periods of mental work with a break.

The purpose of the present study was to examine how an inserted break influences the cardiovascular and central nervous system responses during periods of mental work. Twelve males conducted two 20-min periods of mental work with a 3-min break between them. Cardiovascular and central nervous system responses were measured continuously. In comparison to the baseline, cardiovascular responses increased continuously even after the inserted break, while, on the contrary, central nervous system activity did not significantly increase during the work periods but relaxed during the break. The work performance increased during the second work period. These results suggest that the inserted break proposed by VDT guidelines in Japan was effective in relaxing the central nervous system but was insufficient to prevent the increase in cardiovascular load. The results also imply that taking rests frequently is important not only to maintaining performance but also to preventing cumulative physiological workloads.