Nicodemus came to Jesus “in the night” and I think that the sun was down when he met Jesus and had his now famous conversation with Him. But I also think that Nicodemus was “in the dark” about a few things and came to Jesus seeking light.
“Now there was a Pharisee named Nicodemus, a leader of the Jews. He came to Jesus by night and said to him, “Rabbi, we know that you are a teacher who has come from God; for no one can do these signs that you do apart from the presence of God.” Jesus answered him, “Very truly, I tell you, no one can see the kingdom of God without being born from above.” Nicodemus said to him, “How can anyone be born after having grown old? Can one enter a second time into the mother’s womb and be born?” Jesus answered, “Very truly, I tell you, no one can enter the kingdom of God without being born of water and Spirit. What is born of the flesh is flesh, and what is born of the Spirit is spirit. Do not be astonished that I said to you, ‘You must be born from above.’ The wind blows where it chooses, and you hear the sound of it, but you do not know where it comes from or where it goes. So it is with everyone who is born of the Spirit.” Nicodemus said to him, “How can these things be?” Jesus answered him, “Are you a teacher of Israel, and yet you do not understand these things?” John 3.
Jesus later would say that He was going to return “like a thief in the night” and that surely means that most of us are not going to understand His second coming better than Israel understood His first coming.
Heaven has to deal with realities, with truth. We are but little children and, even worse, some of us are just blinded by wickedness. I often say we cannot explain life to a three year old. Well, the problem is we are not even three years old when it comes to understand Heaven and God's design for us.
For example, Our Lady of Akita spoke true words when she said that fire was going to come from Heaven and entire nations would be decimated but that does not necessarily refer to reality as we see it now but perhaps to reality as we will see it at some point in the future. To understand it consider the following:
Who would have said in Palestine of the first century that the Lamb of God was going to be born there, while His people were completely oblivious to the most important happening in the history of mankind up to that day? He was born and the shepherds were out in the fields. Why are shepherds out in the fields in the middle of the night? Because it was the night the lambs were born. I am from a wool producing region by the Andes mountains, there (and everywhere) sheep give birth all about the same time too. We humans are born at any time of the year but little lambs are all born around the first moon of the spring. The shepherds of Jesus’ time were out in the fields because they had to help the sheep have their little lambs that night.
The time was right also, it was about the beginning of the year in the month of Nisan. Then the lamb for Passover had to be “about one year old, without blemish” to be killed a year later on Nisan 14. Then He also had to be “called a Galilean” and so it was possible for Him to eat the Passover meal one day in advance if the Passover fell on Friday. That was permitted to Galileans so they did not have to spend Saturday on the road and violate the Sabbath. So there was a dispensation that year for Galileans to eat the passover earlier and avoid having to travel on Saturday back to their homes far from Jerusalem. So Our Lord could have the Passover meal and be the True Passover at the same time.
Think of another series of details. That night He did not sleep and the following day was for Him all non-stop suffering. Because He was so tired and physically spent, His heart failed under the exertions of the brutal Roman cross just in time so His legs did not have to be broken... etc. All was prepared to the smallest minutiae, from far constellations, to the moon, the eclipse, the palms the previous Sunday, Pilate's words, his wife’s dreams ... all of it in a manner that no one on earth could have organized beforehand ... so we can believe. Such is the Divine Language singing the rhapsody of salvation. We know His voice. We will hear the whole composition one day in awe but it may be millenia until we can fully understand what we are living through these days. That is why is so important to abandon ourselves to the melody now. We will hear it whole one day.