There doesn’t have to be a trigger for sundown syndrome to occur, but many elderly people have other ongoing issues that can aggravate this condition. Internal changes or external stimuli may contribute to sundowning. Some of these triggers include:
Illness or infection (such as a urinary tract infection)
Low lighting or dimming of the room they are in
An increase in shadows
The inability to discern between reality and dreams
Disruption in the person’s internal clock
Fatigue
Alcohol
Medication
Jet lag or changing time zones