Breakdown of Der Großvater ist im Tiefschlaf, wohingegen die Großmutter eine unruhige Nacht hat.
sein
to be
ein
a, an (eine)
haben
to have
im
in the (used with months) / in the (contraction of in + dem)
Questions & Answers about Der Großvater ist im Tiefschlaf, wohingegen die Großmutter eine unruhige Nacht hat.
Why is the verb hat at the very end of the second half of the sentence?
Because wohingegen is a subordinating conjunction. Just like weil or dass, it kicks the conjugated verb in its clause (hat) to the very end of the sentence.
Could I use während instead of wohingegen here?
Yes, you could easily say während die Großmutter eine unruhige Nacht hat. While während can mean both "during/while" (time) and "whereas" (contrast), wohingegen strictly means "whereas" and is used to emphasize a strong, direct contrast between two situations.
Why is it im Tiefschlaf rather than just in Tiefschlaf?
In German, being in a deep sleep is treated as a physical state or location, so it uses the preposition in plus the dative case to answer the question "where?" or "in what state?". Der Tiefschlaf becomes dem Tiefschlaf, and in + dem contracts to im. English drops the article ("in deep sleep"), but German requires it.
Why does unruhige end in just an -e?