I'd recommend having HR confer with Security and IT as it is still an issue of personal safety and information access. More than once I went into my office, having nothing to do with the branch ops area, at 4 or 5am to get something before an early morning flight. I always tried to seek out the guard who may have been clearing the building as shouting out was better than scaring him and potentially drawing harm to one or both of us. If IT files had to be accessed special steps may be necessary for odd hours depending on security precautions in place.
The HR perspective is likely one of hours worked and supervision. Salaried staff and officers can usually do all they want or need to.
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