Churchill did it. Marcel Proust did it. Mark Twain, Edith Wharton and Truman Capote did it, though the latter said a bed was not required. A couch would work just fine, as long as coffee and cigarettes were available.
I can't relate on that score. More my speed was Wordsworth, who wrote poems in bed but made up for it by walking 10 miles a day, striding all over the Lake District, often with his sister Dorothy.
It makes perfect sense to me, a great expenditure of energy, followed by an equally great period of rest.
(Marcel Proust writing in bed.)