Oddly, as soon as I decided to stop stressing about my sleep patterns, they suddenly became far more sensible!

Not odd at all IMHO -- if your brain is constantly fretting about something you're much less likely to sleep soundly (if indeed you get to sleep at all). As I know only too well. :-/ Of course the problem with worrying about sleep is that it tends to get into a bit of a vicious circle... glad to hear you've broken that. :-)