It does not say, exactly in Canon. Remus says he takes it, and then curls up and goes to sleep. My guess? Harry describes him as looking peaky leading up to the change, so I think that condition may make him tired, and the potion acts as a type of sedative/healant.

To your 'grr' there is also a lesser known argument that the British do not feel things as intensely, and so these british characters will not be so 'emotional' about XYZ.
Bullshit. These are incredible emotional characters; Severus belts off whenever he feels threatened, Remus employs distancing and hiding,HErmione tries to employ her warmth and conenction to people, Sirius is rash and thus rather stupid, and Harry often feels profoundly lonely. That they don't talk about their feelings does not mean that they are not feeling anything.