Working a 24hr shift is rough. Been there, done that, don't really want to do it again. It is not healthy for yourself, unsafe for patients, and unsafe for other drivers on the road. I have not read any studies about this, but I can just speak from experience. This is why I feel 24s are a bad thing. But, on the other hand, if you were allowed to sleep, then you could be rested. Although, I am not so sure the public would be too happy about having to pay taxes or whatever for ambulance services where the crews sleep half of their shift.
There have been times where I went into work for a night shift and a person from the other crew would clock in, check the equipment and go to sleep. Would not see him until morning when it was time to go home. How is that fair to other people who actually have to work? It was brought up and the argument was always settled by what I had stated above "rather be rested".
In my opinion, if you come to work and need to sleep, find a new job or a different shift. If you feel differently, you can paypal me $15/hr tonight while I am sleeping.