Sleep Posture | Mark's Daily Apple:
"Whether you’re in bed, on a cot, or on the floor, the key is to lengthen your spine. You touch ground with your sacrum, lay your palms on the ground, and slowly lower yourself back, taking care to actively lengthen your spine – vertebrae by vertebrae – by pushing through your hands. The result is an oddly awkward feeling; you really do feel longer than normal. It takes a few minutes to get used to it, but it’s an incredibly comfortable way to lie down."