If there are day shifts available, then your employer must make them available to you, assuming that your disability is one which persist permanently or for a long period of time, and your employer will not suffer an undue hardship by providing you with the accommodation.
The question is: how does working days assist you in performing the essential functions of your job, as compared to working swing or night shift?
If you or your physician can succesfully explain this, then you may have a valid disability discrimination claim.
If you can't explain the rationale from a health care perspective, then your employer can refuse the accommodation.
See this link to file a disability discrimination complaint.
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