Objective:
This case-crossover study aimed to evaluate changes in alertness following night shifts among workers in the aluminium industry, and the potential impact of the number of consecutive night shifts and shift length.
Methods:
We estimated alertness on 87 aluminium workers by a 3-minute version of the Psychomotor Vigilance Test (PVT) after both day- and night shifts. Linear mixed models were used for statistical analysis.
Results:
The level of alertness was significantly lower after three and four consecutive night shifts, compared to after a day shift. No significant differences in alertness were observed between three and four consecutive night shifts, nor between periods of three consecutive 8 + 8 + 8-hour versus 8 + 12 + 12-hour night shifts.
Conclusions:
Our findings indicate reduced alertness after three and four consecutive night shifts, compared to after day work. No significant dose-response effect was observed.