Please help... Caught dozing during work

2 employees were caught dozing (very short time - less than a minute according to witnesses) and will be subjected to disciplinary action.

the fact is the employer just change the current shifting schedule to the following schemes:

I. shift A - 2 days 12hrs(am shift) - 2 day rest days - 2 days 12hrs (pm shift) - one day rest day - 2 days 12hrs(am shift) - so on (for one month then transition to B-C sched)
II. shift B and C - 5 days 12 hrs work - 2 days rest days (AM / PM shift respectively for 1 month then transition to Shift A sched)

its taking at toll to most of its employees as most of the work demands physical exertion, process monitoring, repeatitive tasks, and focus as they work in an environment filled with mechanical and chemical hazards... all the while standing or walking continuously for 12 hours... (they were not allowed to even sit) with occasional break of 45min and 30 min

can they justify that the sleeping event is a consequence of these seemingly very demanding and maybe unhealthy work schedule? thus sparing them from the punishments on the ground that the new policy is the main cause of the action

thanks

i suggest that they explain and apologize, but i would not always consider this a terminable offense