It seems that the pace of change in music waxes and wanes, and does not seem to be accelerating. The twenty year gap from 1955 to 1975 is enormous. From 1995 to 2015, not so much.
Another interesting topic would be the effect of body temperature on sleep latency and/or quality (or possibly temperature of selected body parts--there is some buzz about the so-called "cooling cap" for insomnia lately, for example).
To me it seems a big breakthrough for being able to trim sleep time down substantially would be some technology that allowed a person to pass through the lighter stages of NREM sleep more quickly so that you could spend the majority of sleep time in slow wave.
First a plug for the best Sleep text by far, "Principles and Practice of Sleep Medicine", by Kryger, Roth, and Dement. If you don't have this, you need it.
To turn off the circadian alerting, it would suffice to suppress cortisol.
I would think that there is plenty of low hanging fruit to exploit before that though. After well known sleep hygiene measures have been addressed, and pathologies excluded, the largest remaining drain on sleep quality is maladaptive emotional processing. See Barry Krakow's "Sound Sleep, Sound Mind" for lots of detail on this. This book is rather unusual in making a big deal of the link between poor emotional processing and poor sleep quality, but dude is a very highly regarded sleep specialist who had been running a top-notch sleep clinic for many, many years, and not to be pooh-poohed lightly.
I have the sense that there's something wrong with this division into "adopters" and "non-adopters". The lack of increase in cryonics-adopters while pro-cryonics evidence has been coming in does not mean that there is one group that updates their cryonics decisions rationally (the adopters) and one group that does not (the non-adopters). If that were the case then there would be an increase, as the rational ones gradually got on board as evidence came in. The stasis in the adoption curve wouldn't just mean that the current non-adopters are irrational for not getting on board, it would also mean that the adopters were irrational for getting on board too soon, before the good evidence came in. Unless we want to say that from the get-go the pro-cryonics case was super strong.