A survey of control room operators in a nuclear power plant identified practical activities for maintaining alertness during the early morning hours. Nine on-duty operators rated 16 activities they were allowed to do on shift. Activities most effective for alertness were splashing cool water on the face, drinking coffee, and doing things that used muscles. The least effective activities were passive monitoring and studying for exams. The large range of ratings indicates that activity has a major role in operator alertness during the early morning hours.
Jensen, Roger C., "Alertness-Supporting Activities for Control Room Operators in Automated Industrial Plants" (1999). Safety Health & Industrial Hygiene. 25.