Hi Faith I think when looking at sleep and CRPS it's important to take a multi-modal approach. Finally, I am getting there with sleep thanks to a good pain management doctor and occupational therapist and lots of persistence on my part. Start with considering medical management and whether your boyfriend is getting adequate pain relief from his night time medications, including whether he is on meds like anticonvulsants (gabapentin or Lyrica), antidepressants (eg trazone or endep) and other meds. If he's the right type of meds it will help slow his nervous system down and have the added side effect of making him drowsy at night.

It may also be important to look at the position/environment/ he's sleeping on/and sleep hygiene issues. Different people accommodate their painful areas in different ways. For example, depending on what area of the body is affected some people sleep in recliners or use pressure care mattresses on top of their beds, or lots of supporting pillows to support a limb etc. As far as sleep hygiene goes, unfortunately your boyfriend's current crash and burn cycle will be self perpetuating for further bad sleep. Sorry to say that.... I am sure he knows already and is just trying to survive day-to-day. At some stage, the only way of improving it will be to have the same getting up time regardless of how much to sleep he has had if any. It is the time you get up which trains your circadian cycle. If you Google's sleep hygiene and circadian cycles you'll find some more information. Sleep can get much better if you tackle one bit of the problem at a time.
Good luck!