Be borne in on somebody
Definition 1 of 1
Pro Tip 1/3Sudden Realization
Use it when someone suddenly understands something important that they didn't see before. 
As he read the letter, it was borne in on him that he had won the scholarship.
Pro Tip 2/3Emphasis on Impact
Shows that the realization has a strong, often personal, impact on the person. 
After the speech, the gravity of the situation was borne in on the audience.
Pro Tip 3/3Not Instant
The phrase implies a process—understanding may take time to develop fully. 
While working on the problem, it was slowly borne in on her that there was no simple solution.