suspected swayed back when stretchlying

Both anteverting too much or too little can cause pain and problems. With extra stretch in the back you can tolerate some distortion of the L5-S1 and other spinal joints better. Try to keep your pelvis neutral (as described in 8 Steps to a Pain-Free Back) as you stretchlie.

Think I was having same sort of problem..  what I got in the review at the foundation class was . . . it is important to have the pillow under the shoulders because IT takes sway out of the back.  Then it is much harder to over antivert.  finally slept longer than my teenage daughter last night.  Hence the 205 am post.  Slept too much last night  ;D

I sleep better and longer with stretchlying, but what about that pillow under the knee?  It looks like this could cause shortening of the hamstrings. Dr. Janet Travell cautions this in her seminal book on myofacial pain.

Perhaps you mean short psoas muscles ? It wouldn't cause short hamstrings - if anything, the opposite, but not significantly.

A pillow under the knees does allow the psoas to adjust to a shorter resting length (just like prolonged sitting does), but I make this recommendation anyway for the following reasons.  Most people have short psoas muscles to begin with - the pillow under the knees simply accommodates for the shortened muscles. If you persist in using the pillow under the knees and do nothing else to stretch the psoas, you are perpetuating the short psoas problem, but if you do away with the pillow, your tight psoas is likely to cause your back to sway and compromise your discs / nerves / muscles / blood flow around the spine. My recommendation is to use a pillow (or two or three or...) under the knees if that feels comfortable, make a mental note that you need to stretch your psoas, and do so by learning to walk with the heels remaining on the ground in the rear (push-off) leg for an extended time. This way you get a psoas stretch with every step you take, you don't have to worry about shortening your psoas, and your night's sleep is not disturbed by distortion in the spine caused by a tight psoas.