Been on bed rest for over a month on back. sitting up is hard with constant dizzy head. how long should i sit up each day? hard to do with dizzy head

Go slow: You've been flat on your back for over a month. The condition is called orthostatic hypotension. There is no routine on how to recover. Just gradually try to sit up. When the dizziness gets to you, lower back to a level that is tolerable. Wait awhile and try again. Don't force yourself. Easy does it. I went through it myself once. I passed right out the first time I sat up. it takes time.