In all honesty, my sleep patterns are probably worse since FIRE. When I was working, I was always tired at bedtime, knew I had to get up early for work (which encouraged me to go to bed), and had little to look forward to the next day. I didn't suffer from work dreams at all and usually slept fairly sound.
Now I often stay up late, knowing I don't have to go to work the next day, and knowing I can probably catch a nap if I need one. But, if I take a nap, I'm more likely to stay up late, just perpetuating the cycle. I also wake up early when I am stoked about the upcoming day, usually a road trip or the like, which results in being tired before ever getting on the road. The one thing I notice is that being tired is less painful than it used to be. It used to come with a headache, which was just made worse by caffeine. Now, when I'm tired, I'm just tired, and seem to be able to recharge a bit by relaxing on the sofa for 15-20 minutes.
I'm also recovering from a (hopefully fixed) chronic health problem that severely affected my sleep. I'm looking forward to some 100% pain free sleep, which I haven't seen in months...