schlafend
sleeping
Being in a state of sleep.
Bitte sei leise, das Baby liegt schlafend im Nebenzimmer.
Please be quiet, the baby is lying asleep in the next room.

sleeping / dormant
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sleeping
Being in a state of sleep.
Bitte sei leise, das Baby liegt schlafend im Nebenzimmer.
Please be quiet, the baby is lying asleep in the next room.

'Schlafend' (sleeping) is the present participle of the verb 'schlafen' (to sleep). This form describes an ongoing action and is often used like an adjective before a noun or as part of the predicate.
Der schlafende Hund bemerkte den Postboten nicht.
The sleeping dog did not notice the mail carrier.
You can use 'schlafend' (sleeping) directly before a noun ('der schlafende Gast' — the sleeping guest) or as a description of state with the verb 'sein' (to be): 'der Gast ist schlafend' (the guest is sleeping).
Weck den schlafenden Löwen nicht.
Don't wake the sleeping lion.
You can recognize the figurative meaning 'inactive' from the context. It is used for things or abstract concepts, not for living beings that are currently sleeping. Typical nouns are 'Konto' (account), 'Mitgliedschaft' (membership), or 'Talent' (talent).
In ihm schlummern noch viele schlafende Talente.
There are still many dormant talents slumbering within him.
In a business context, the combination 'schlafender Gesellschafter' (silent partner) is a fixed expression. It refers to an investor who only provides capital but does not work in the company.
Er ist nur schlafender Gesellschafter und nicht in die täglichen Entscheidungen involviert.
He is only a silent partner and is not involved in the daily decisions.
active
'aktiv' and 'schlafend' can be opposites when the topic is activity or operation. 'aktiv' means that someone is doing something, moving, or that something is functioning. 'schlafend' literally means that someone is sleeping. Figuratively, it can also mean that something is not currently being used, but can become active again later. For people, 'schlafend' only fits the state of being asleep; for general inactivity, you would more likely say 'passiv' (passive) or 'untätig' (inactive / idle).

Nach dem langen Schultag sehe ich im Bus meinen schlafenden Freund.
After the long school day, I see my sleeping friend on the bus.
Tara bleibt im Verein aktiv und organisiert jeden Monat ein Treffen.
Tara remains active in the club and organizes a meeting every month.