Can they stop paying disability

[cthorsedog]

North Carolina
My husband was a pilot for a major airline and was forced to go on disability (privately insured not social security) because he had to start taking a medication that could not be taken while flying. He has been on the medication for several years and continues to need it to treat severe insomnia. It is classified as an antidepressant which is why they will not let him fly. Recently, he was contacted by the insurance company and they indicated that they wanted him to go back to work. Since this would involve not taking the medication, he is concerned about what to do. Can they force him to stop the medication and go back to work, or can they refuse to pay his disability claim if he doesnt go back to work, with a doctors statement that he needs the medication. He would love to go back if he could fly and treat the insomnia at the same time. However, he does not want to go back if it just means not taking his medication and not being able to sleep.