Any good suggestions for a weakness to light?

Name: Dijorno
Age: 20
Race: Human
Elemental power: Light
Elemental weakness: (What would light be weak too?)
Background: He comes from an orphanage. From an early age he had some proficiency with magic, which he used to lord over the other children in the orphanage. This has led to some problems of ego. Eventually he would leave the orphanage to seek further power.