Light Therapy for Internet Gaming Disorder

The light therapy will be administered by custom-made light boxes (LED) with adjustable brightness. The light intensity will be set at 5000 Lux. The intervention will consist of daily exposure for 30 minutes in the morning. The whole intervention includes 14 days.

The light placebo intervention will be administered by custom-made light boxes (LED) with adjustable brightness. The light intensity will be set at less than 200 Lux. The intervention will consist of daily exposure for 30 minutes in the morning. The whole intervention includes 14 days.

The training aims at associating gaming pictures with negative words and pictures of healthy activities with positive words. Gaming pictures are always presented with a pair of negative words. Pictures of healthy activities are always presented with a pair of positive words. Each picture is presented with a fixed pair of words. Participants will be instructed to select one word to get the most monetary reward. Specifically, selecting a fixed word of the word-pair will be associated with a high probability (eighty percent) of getting a monetary reward and a low probability (twenty percent) of no reward, and probabilities will be reversed for the other word. Each training run will comprise 100 gaming picture trials and 100 healthy-activity picture trials, presented in a pseudo-randomized order. Participants will receive two training runs every day. The whole training includes 14 days.