It's understandable that you can't sleep on 50mg of prednisone. It's a very high dose for PMR. Most starting doses are 15mg - 25mg and it's reduced fairly quickly down to 10mg, after which reductions are made more slowly. Australia's standard start dose for polymyalgia rheumatica is 15mg. Is there some other reason your doctor has you on such a high prednisone dose?