Taking the first step
Care
The first conversation should exclusively concern the “caring” aspect. So, no announcements of sanctions or anything like that – this would imply that options for conversations have been ignored in the past, missing opportunities to intervene earlier.
The recommendation is: Start a conversation early on. Most employees wish to be addressed.
Naming noticeable signs
You shouldn’t ignore signs but briefly mention them (“Your headache is back? I am sorry. Well, see how your work goes. Otherwise you better go home.”)
If this occurs frequently, make an appointment for a conversation.
Occasion
Changes in performance and social behavior are reasons for a conversation. As a supervisor, it is these aspects for which you share responsibility within your department.