Mush
PIP does not directly consider problems that you have with sitting and lying down, you would have to include such problems in your answer to issues you have completing the PIP activities.
Have you looked at our PIP Claim guide, it may help you complete the form.
www.benefitsandwork.co.uk/help-for-claimants/pip If you have further questions then please reply to this post and we will do our best to help.
Gordon