Thanks for your appreciation and for sharing your experience and conclusions.

Sleep problems very frequently pop up in this discussion. I can relate to that, because I too have interruptions to sleep, but I have found a way of dealing with it. If I can't sleep through, I get up, do some work for 1-2 hours , and go back to sleep. Since I typically go to bed by 21:00 and get up by 05:30, I have enough down-time. And the nightly hour of work can be exceedingly productive. Somewhere I have read, but I can't find the source anymore, that this sleeping pattern was quite common in medieval times. An, you nailed it with your closing statement: "each individual probably ought to consider not only the statistics but also their own psychology."

Thanks for that.