I also have this old bookmark that may help. You can skip to the summary if it is too much to digest. Reading the whole article may send you off to sleep, but there are some good snippets."Drugs for treating sleep disturbance
Sleep disturbance, and in particular persistent wakefulness and night-time restlessness, can be distressing for the person with dementia and disturbing for carers. Many of the drugs commonly prescribed for people with dementia can cause excessive sedation during the day, leading to an inability to sleep at night.
Increased stimulation during the day can reduce the need for sleep-inducing medications (hypnotics) at night.
Hypnotics are generally more helpful in getting people off to sleep at bedtime than they are at keeping people asleep throughout the whole of the night. They are usually taken 30 minutes to one hour before going to bed.
Chlormethiazole is generally well tolerated by elderly people, although some cannot take it because it produces an unpleasant itching sensation in the nose. Benzodiazepines (see section on drugs for treating anxiety) such as temazepam are frequently prescribed.