Restlessness in the later day time to evening hours is often referred to as "sundowning".  Sundowning is a dementia-related symptom that refers to increased agitation, confusion and hyperactivity that begins in the late afternoon and builds throughout the evening. This symptom of dementia is caused by a disruption in the body's internal clock.  It is typical that an individual with Alzheimer's disease may want to "go home" or "go pick up the children," since these were typical activities completed in the afternoon in their past. This feeling of urgency often cannot be expressed verbally, but can be observed as restlessness or agitation.  Processing daily information can be physically and mentally exhausting for an individual with Alzheimer's disease.  This intense concentration can be overwhelming after several hours.  By late afternoon a person with dementia may be exhausted, unaware of the time and over-tired. 

Your mother's sleep patterns also might be contributing to this behavior. It is important to know that older people require less sleep, about six to seven hours on average.  If your mother is napping during the day or goes to sleep too early, this may contribute to her restlessness in the late afternoon. Also, she may awaken in the middle of the night, become disoriented and proceed to wander.  Try to improve the quality of sleep for your mother by minimizing drinks a few hours before bed, making sure she is comfortable, uses the bathroom and takes medications.  Also, a nightlight can be helpful for confusion if she wakes up during the middle of the night.    

In order to try and minimize issues, always check to make sure your mother is not hungry, thirsty or in pain.  Drinking caffeinated beverages, daytime napping and noisy environments also can aggravate your mother.  It is helpful not to plan demanding activities or outings in the afternoon hours.  For you as a caregiver, it is important to remain calm when dealing with this symptom.