I woke up around 1 AM. Sore, and feeling too warm, just barely starting to perspire. Body Battery is 62, which is only fair. According to Garmin, it may take a few days for the score to reflect the actual energy state of your body. It also collects data on your VO2Max and uses that, and the VO2Max score evolves over time.
More advanced Garmin watches support a training load metric that is more precise in giving estimates for recovery. So do all the Polar watches. Some even try to quantify estimated muscle strain. I suspect the basic watches are all using TRIMP (for TRaining IMPulse), which is a formula used to measure cardiovascular load based off multiplying your heart rate by the duration of an activity, but they don't perform as complex calculations to support recovery estimates (all the widgets make calls to an API specifically tailored around physical fitness and activities, that has various extensions for different models with different capabilities).
My watch does have a few training plans for running and cycling that looks at your data and tries to formulate a plan, but I don't see one for other activities like walking. I might have to check out a forum, or perhaps even consult with a doctor, personal trainer or physical therapist.
I made a cup of American ginseng, which is something I've sometimes found beneficial when I am dealing with being fatigued. Hopefully I get in a nap before church. My experience with this kind of poor sleep, with a night cut short, is due to either too little or too much exercise. Occasionally it's due to random noises in the night (I'm a lighter sleeper, I've known that for a while), or a combination of the two. If my nervous system gets switched over to too much sympathetic activity, poor sleep seems to be the result. I also suspect there is elevated cortisol happening, which is why I think the ginseng could be helpful. It seems to be better for me to exercise earlier in the day, and to be actually somewhat lazy the rest of the day, especially 3 hours or so before bedtime (not just avoiding exercise at night, which is something I've heard about for a long time).
Sometimes Florida can be tough because I have found I actually sometimes sleep best with a room that's about 72 degrees, if the air isn't directly blowing on me. But in Florida, not only is that expensive, sometimes it's impossible to get a room that cooled. This past summer was brutal. One day the air conditioner was going full blast and the temperature didn't fall below 78 in the daytime (the unit is relatively new, too). We live in an older duplex unit, though, built around the late 60's, so that might be a factor.