After Light got the Death Note, he started writing criminals' names and killing them. Even after L made his first appearance and said that he would find Kira, then Light was thrilled up and accepted that as a challenge.
As we all know Light was the 1st performer in his academics from the start. But when he got the Death Note, then he was certainly spending a lot of time on planning how to kill, and also observing how the Death Note works. But even after all this pressure of killing and L coming to find him, he maintained his academic performance.
So does that mean Light was so talented that even without studying he was able to come first in his academics, or was he spending enough time in academics as well? Is there anything specified in the anime or manga about how he was managing his time between his studies and by writing names in the Death Note so that he would not get caught?