Is deep sleep resulting from psychiatric medication, which leads to missing prayers, considered a legitimate excuse? And how can this situation be dealt with?

If sleep overcomes a person until the prayer time expires, there is no sin, for the Prophet, peace and blessings be upon him, said: "There is no negligence in sleep." The prayer should then be performed upon waking up. However, if one wakes up before the time expires, it is obligatory to hasten to perform it, otherwise, one would be sinful. There is no sin in sleeping before the prayer time begins, but one should take measures to ensure waking up.