Psychiatrymiddle twist
A 13-year-old boy's marks have fallen steadily over 12 months and his teacher reports that he dozes in afternoon classes, is irritable and forgets instructions. His mother says he snores every night, sometimes stops breathing and then gasps, and has started wetting the bed again. He wakes with a headache and refuses breakfast. His tonsils are large and he breathes through his mouth. School hearing testing this year was normal. Which one of the following investigations is most likely to explain his deterioration?