Tilting a bed to make use of gravity is something NASA have been doing since the early 90's. I would consider their opinion as being worthwhile, especially when they go to the trouble of publishing their conclusions and thoughts. I hope you enjoy watching the videos. There are more interesting videos on her channel.

Published on 19 Feb 2013
In this 2012 talk at NASA's Ames Research Center, Dr. Joan
Vernikos explains how during these technology-rich times we're moving (and using gravity) less and how that is slowly undermining our health.

http://www.youtube.com/watch?v=SnEpg1MOoKg

Published on 19 Feb 2013
Dr. Joan Vernikos visits NASA's Ames Research Center and tells the story of George Mueller, and how simply standing up frequently throughout the day helped this 91 year-old get back on his feet. http://www.joanvernikos.com

http://www.youtube.com/watch?v=qSoRmaNLoiw

Published on 18 Feb 2013
In this 2012 talk at NASA's Ames Research Center Dr Joan Vernikos, author of "Sitting Kills, Moving Heals", explains how what we've leaned form astronauts has shown that so many of the ills affecting our health today are due to not moving enough throughout the day.

http://www.youtube.com/watch?v=fglQLFCAVeY

Published on 19 Feb 2013
In this 2012 talk at NASA, Dr. Joan Vernikos explains how a lifestyle of frequent, low-intensity, non-exercise movement throughout the day is a great way to remain healthier.

http://www.youtube.com/watch?v=TKjr-az3xeE