دَخَلَ الطَّبِيبُ وَالْمَرِيضُ نَائِمٌ.
The doctor entered while the patient was asleep.
'Al-marīḍu nāʾimun' presents the state obtaining at the moment of entry, favoring a circumstantial analysis. In a different sentence such as «دَخَلَ الطَّبِيبُ وَجَلَسَ الْمَرِيضُ» ('The doctor entered, and the patient sat down'), the second event may be an independent report.
Test whether the clause expresses a concurrent state and whether its link to the relevant participant in the main event is intelligible.