بسم الله الرحمن الرحيم والصلاة والسلام على نبينا محمد وعلى آله وصحبه أجمعين
If you are sick and cannot find any other medication which is less sedative then you have an excuse. Obviously you must try your best to prepare yourself to wake up for example asking a family member to wake you up, set the alarm clock, sleep early.
Maybe you can speak with your doctor about the issue and mention that you need to wake up for prayer.
I hope that you will be cured and can be free of medication.
Allah can easily cure you so it is a test no doubt and you are rewarded for being patient. So you are only required to make the causes for waking up to the best of your ability.
Below I found a discussion thread which may provide more advice. Otherwise I advise to speak with a shaikh or a knowledgeable, pious person preferably a known shaikh from the Arab and Muslim countries on the manhaj of the salaf us saleh (the pious predecessors). You can reach them by phone and if you can't speak Arabic then ask somebody who can ask for you.
https://www.ummah.com/forum/forum/f...6555-taking-medication-and-waking-up-for-fajr
And Allah Knows Best.