Sleep medicine can be done by neurologists, pulmonologists, and ENT doc's. My understanding is that reimbursement is currently very good for sleep medicine and that practioners usually end up making ~200K or more. Palliative care is often done by the anesthesioloigists who have training in pain management, but there are also a lot of FP's and internists who serve as palliative care physicians. I think that almost anybody with an MD who takes the time to learn pain management can be hired to do palliative care. I think that one reason for this is because there is very little malpractice risk in the palliative care setting, since a large part of malpractice settlements are paid for shortened lifespans or loss of ability to function or work which usually isn't an issue in palliative care. The only cases that I've seen with palliative care is regarding overdose or inadequate pain control, but even then, I don't think the lawyers aggressive pursue these because the payoff's are so low. The same actually goes for a lot of cancer management issues, they don't get sued for too much either because jurors tend to see cancer as a death sentence irrespective of what the physician does. Cancer misdiagnosis is a major reason for physicians to get sued though, since jurors see delay in treatment as harmful to patients.