Nicodemus comes to Jesus at night. It is a sign of respect and his desire to learn at the master's feet. When he comes to Jesus to shine some light on his own uncertainty, the light of Christ reveals more about Nicodemus than he bargained for. He learns that he had a vision problem he didn't know he had, but also that Christ can fix it.
When the light hits us, sometimes it hurts. We see things we don't want to see and we have exposed things we don't want God to see (as if He didn't already know). The flesh wants us to retreat from that all exposing light, but when we move toward Jesus and not away, he makes us new and destroys the darkness in our lives.
When Jesus does His work of delivering us from the darkness, He continues His work by filling us with His Holy Spirit. He always keeps His promises this way. When we are filled with the Holy Spirit, and He drives us into His action, we can truly experience the kingdom of God on earth. Your will be done, Your kingdom come happens when God's Spirit drives us to action.