Based on the context and the answer, generate a question. 

Context: After a long flight we sure love to get a good sleep . But it 's afternoon in Beijing and we need to adjust to the local time . We took a quick nap and woke up in the early evening in time to take a stroll around the neighborhood . Our hostel is nearby the old drum tower which is located near a busy street .

Answer:

Once you 've entered a new region , your body must acclimate to the time difference



Why does a long flight require the speaker to then have to adjust to the local time ?