Bettschwere [German]: A state of consciousness too ponderous for anything but sleep. Noun.
Have you ever awakened on a day off, remember that you had made plans to get out and enjoy yourself, but ended up just gazing out the window at the bright, clear, inviting day before turning over ab going back to sleep, breathing a guiltless sigh in your delicious torpor? This peculiarly decadent frame of mind is not the kind of exhaustion that comes from hard work or lack of sleep. It is simply, as the Germans say, a state of “bed heaviness” – Bettschwere (BET-shvare-eh) – in which you realise you are temporarily feeling too heavy to perform anything as mentally and physically demanding as getting out of bed.
– They Have a Word For It: A Lighthearted Lexicon of Untranslateable Words and Phrases, Howard Rheingold. (p. 150-151)