We have as yet not even determined if you are subject to the ADA; we know nothing about your position, what you are and are not qualified to do, what your job duties are, how your job duties have changed, or what medical condition you are claiming as a disability. It takes more than a doctor's note to make the ADA applicable. So we cannot say whether your demand...uh, request...is reasonable or not. There is no bright line and "reasonable" is a moving target, as a friend of mine would say.