Studies in the UK and elsewhere have identified that being fatigues due to broken sleep patterns is equivalent to drinking alcohol in terms of performance degradation
Nothing related is mentioned at the largest US HEMS operator in training or any directive. Until a few years ago each base could set their own work schedule for local or crew conaiderations as long as duty periods were staggered program wide such that bases weren't changing crews simultaneously. Management changed all the local scheduling imposing a standard schedule: one could report on Monday for 3 days, a 24 hour break after signing out Wednesday, and 4 nights. The mirror image started 4 days on Thursday, 24 hours after the Sunday duty and 3 nights Monday-Wednesday. As weekends were the busy period for scenes the guy flying the 4 night period faced extra challenges.
I can't count the number of times the night pilot relieving me on days has told me that he had no sleep that day and was hoping for no callls so he could sleep, or that he had a full day planned and hoped the next night was slack. A 24 hour break is in no wise sufficient to transition days to nights.
To the company's credit they never challenged me for declining a flight. Management has since changed at my local base, and is not tolerant of missing flights
for any reason regarding the requirement to show uo well rested as the rule, regardless.
Lacking any fomal method of appraising my mental capability, I used the rule that if I had to read the weather reports twice before accepting dispatch, I would decline the flight I also attemptd to evaluate my medical crew's status and would decline on my authoority if i judged
they were not at full capability, they wee to be included as a resource to maximize safety