Yes that’s the position. Good to see it verified in the study. Having a partner and sleeping in the same bed can lead to alterations from the optimal sleeping position, especially sleeping on the back is not good. Sleeping on the back is also one of the main causes of snoring, which often occurs in people which have a big belly and can’t really sleep lateralish anymore.

Sleep quality is important too and one big factor is not to go to sleep with a full stomach. Sleep quality will suffer because of the active digestion which probably will not let the glymphatic transport do it’s job properly.

Also good to know that “…low doses of alcohol (0.5 g/kg) increased glymphatic clearance…”.