It seems that the main focus of the article is on the difference in brain activity, not the sleep time. I would imagine that the time to sleep is not as important as the quality of the sleep thus attained.
I agree, and as such this article leaves my main question unanswered: with a bed that rocks (or a hammock), could I get the same amount of rest in less time?
In other words, what is the ratio of sleeping hours in a non-moving bed to a rocking-bed?
> could I get the same amount of rest in less time?
I'm dubious of anything that claims to pull this off. My own failed attempts have convinced me that sleep is not something that can be lifehacked. There is some variation in sleep requirements between individuals, but you and I each have a number (probably ~8 hours) below which our bodies start getting cranky. There are loads of studies showing that any form of sleep deprivation -- and I would include here trying to optimize down your overall sleep time -- has reliable, long term negative consequences. What's more, there seems to be an unusual level of consensus on this subject. (I say 'unusual' because medical researchers never agree on anything. :-)
This is basically true, but it doesn't necessarily all have to come in one 8 hour shot. The past month I've been taking 10 minute naps once an hour from roughly an hour before lunch on through about 6 in the evening, and it makes my working hours much more focused and my after-work hours feeling much more refreshed.
The journal article indicates that the rocked subjects went from a waking state to deeper states of sleep quicker than than those non-rocked... So that should yield a time savings.