He's having Sun-downer's Syndrome
Step-by-step explanation:
The confused elderly patient should be suffering from Dementia or Alzheimer’s disease which causes this Sun-downer's syndrome. This behavior is been exhibited in the late afternoon or evening. It is mainly due to the hormonal imbalance.
These patients tend to loose themselves and the after math is that they don’t remember a single thing of what they did or said during the previous night. It should be a result of the neurons that has stopped working in the brains.