Alzheimer's disease is a progressive neurodegenerative disease and the most common type of dementia and was first described by Alois Alzheimer in 1906. Although it affects 50% of people older than 85, it is not a normal part of aging. Today, around 50 million people suffer from Alzheimer's disease and it is estimated that the number will triple by 2050. It is assumed that the aggregations of tau-protein and beta amyloid have a key role in the pathogenesis of the disease. Medications that are currently approved for treating this disease are three acetylcholinesterase inhibitors, one N-methyl-d-aspartate receptor antagonist, and two monoclonal antibodies. Its main characteristics are memory and thinking loss, mood disorder and loss of function. Almost all patients will develop neuropsychiatric symptoms. Sundowning is not a diagnosis, but a cluster of symptoms and can be defined as “occurrence or exacerbation of behavioral symptoms in afternoon or evening hours” and is characteristic for those suffering from moderate or severe Alzheimer's disease. Its etiology is still unknown and is first mentioned in 1941. Main symptoms include irritability, nocturnal behavior, aggression, hallucinations and apathy. Diagnosis is clinical, and treatment always begins with nonpharmacological approach, such as music therapy, light therapy, aromatherapy, caregiver education, background noise reduction, and following a routine. Pharmacological approach is always the second line and includes mainly acetylcholinesterase inhibitors and antipsychotics.