Can you get disability insurance if you are on bed rest?

You have not stated the reason for the bed rest. Assuming that it is because you are recuperating from an injury or a medical condition, the underwriting guidelines of the disability insurer to which you are applying may provide that a further disability (loss of earnings) from that condition will be excluded in the future. The exclusion may be permanent (for the whole duration of the policy), or it may end after a specified period of time.

When applying for disability insurance, it is generally necessary to document current earnings. This is because disability insurance, like other kinds of insurance, is intended to make you whole (or nearly so), and is not intended to be a moneymaking proposition. Assuming that you were gainfully employed prior to the bed rest, the insurer will likely deem that level of earnings to be your baseline.