Your doctor will take a full medical history to rule out possible underlying causes of a sleep-related eating disorder. Certain medications, for instance, for insomnia or depression, can cause a sleep-related eating disorder.
Your doctor will likely also recommend a video-recorded polysomnography (sleep study). This is a painless assessment during which you will have sensors attached to your body while you sleep to observe behavior and to detect whether you have other sleep disorders.
Read more about polysomnography.