Sundowning is a phenomenon unique to Alzheimer's disease where the person becomes more confused and agitated in the late afternoon and early evening. Several theories have been proposed about why sundowning occurs, such as increased confusion due to darkness and shadows, fatigue, and a reduced ability to tolerate stressful situations. The best way to approach sundowning is to make late afternoons and evenings as simple and relaxing as possible. Reduce distractions or unscheduled activities, and keep rooms well-lit until bedtime.

"Sundowning" is very common - Mum has been doing it for about 3 months now; her 'desire' to 'go home' ; her failure to recognise me and her ability to tell the time are always worst in the evenings.

BUPA have a book (free to order via their website ... st-a-guide) called 'Caring For Someone with Dementia' which is very useful reading and has lots of helpful advice on dealing with the various aspects of this disease.