I seem to be having less trouble with bouts of unproductiveness ever since I started sleeping 9 hours (at least) almost every night. This practice was discussed just the other day here on HN [0]. I've been doing it for a year or so. I'm not saying that my periods of reduced productivity are completely gone, but they seem to be shorter and less severe. [0] https://news.ycombinator.com/item?id=7965065
I put a lot of the productiveness down to other factors at work. I'll see if I feel more productive next time she is at a conference and I get the chance to sleep more.