librocubicularist
n. one who reads in bed

Update: An alert reader points out that this is not a proper English word — it was proposed by Christopher Morley in his Haunted Bookshop (1919):

‘All right,’ said the bookseller amiably. ‘Miss Chapman, you take the book up with you and read it in bed if you want to. Are you a librocubicularist?’

Titania looked a little scandalized.

‘It’s all right, my dear,’ said Helen. ‘He only means are you fond of reading in bed. I’ve been waiting to hear him work that word into the conversation. He made it up, and he’s immensely proud of it.’

In any case, etymologically librocubicularist should mean merely “someone who does something with a book in a bedroom.” Apologies for the error, and thanks to Eadwine for pointing it out.