Hi Leanne - Sundown syndrome is common in people suffering from dementia. Directing them to familiar activities may help disorientation. Here are some activities that may help, you may set up one at time or have two or three activities set up daily; depending on how many people you have to help with supervision.
Go to charity shops and buy lots of colourful children/babies clothes
Wash the clothes and place in a basket.
Place basket of clothes on a table and place two empty baskets nearby.
Ask resident to 'help' you sort the clothes by colour: white in one basket and colored into another.
Two basins with some warm water; one with soapy water.
Put dishes (unbreakable) in the soapy water basin.