So wearing a sleep mask and earplugs definitely reduces the number of times I wake up (3.6 to 2.5) and the amount of time awake (17.4 to 12.8). However, it didn't seem to do much for the amount of deep sleep I got (37.4 to 38.3). I rarely felt tired during this time (didn't really want to take a nap), but I also didn't feel particularly energetic. I don't have a better way of describing it. There was also no real increase in productivity during the time of this improved sleep.
These results are confounded a bit by the fact that I also cut out caffeine for all but one day of this trial. I don't think the results are largely due to that though. One day, I intentionally drank an above average amount of caffeine and that was the night I only woke up once for two minutes and had the second highest amount of deep sleep ever.
I did notice that I had a headache for three days after quitting. Which seems like withdrawal...that isn't cool. I also noticed I didn't have the afternoon dip after I got through the headaches. So I probably will continue to avoid caffeine even though it doesn't appear to directly affect sleep.
Bottom line....a lot of waking/wake time is bad for deep sleep, but there is clearly more to increasing deep sleep than just sleeping through the night.
I am going to try experimenting with 800mg of Magnesium now. There is a lot of anecdotal evidence in forums and from Tim Ferriss that it improves sleep.