Mmmm...I'm not that active in the bedroom nowadays, but, never had a problem with keeping it well oiled. There is a certain satisfaction knowing one is sleeping close to a thing of beauty that one is passionate about.....
Lomo.co.uk sells extra long drysacks like the ones used on canoes for £12. I think they would be permeable to moisture in the long term but would be great for smoothing out the peaks in humidity you get in a bedroom.