May I suggest polyphasic sleeping? I've been doing the dymaxion schedule (30 minutes every 6 hours) and my anhedonia is pretty much gone. What's in place, however, is pure euphoria. It may be difficult for some, because the personality differences are huge, but if you cannot keep up exerting tremendous effort into living, it could be a possible change. My only worries starting, was that I was too relaxed and calm. It almost felt like nothing affected me and my sense of fear was nonexistent. Whether this is closer to nirvana or insanity, I don't know, but it's been nice. And the overthinking and hyperawareness that came with a fresh 9 hours of sleep is gone.