A similar relationship between control activities and alertness fell short of significance ( p < 0.09), indicating nevertheless that control activities tended to be highest when alertness and tension were also highest, and vice versa.
Shift-workers’ alertness trend recorded in the work place is comparable to the one reported in controlled laboratory conditions, i.e., an increasing trend across the day, reaching its maximum in the afternoon, decreasing thereafter, first slowly, then steadily to reach its minimum between 02:00 and 06:00 ( Cariou et al., 2008 ).