The 36-Hour Day offers practical advice for dealing with such problems. An enduring bestseller, widely praised as "the best guide of its kind," this is the book's revised and updated third edition. The book was first published in 1981.

Persons with dementing illnesses, authors Mace and Rabins note, may not get enough activity in the day to make them sleepy at night, or they may doze too much in the day. Boosting activity at home or at a day care center, and taking the person on a long walk in late afternoon may promote sleepiness. Efforts to prevent napping also may help. Alternatively, if the person must nap, caretakers should try to rest at the same time themselves.

Tranquilizing drugs taken to control behavior also may promote daytime drowsiness. If this is a concern, ask the doctor whether most of the medication can be given in the evening. This tactic also may reduce nighttime restlessness.

Some persons have disturbing dreams they cannot distinguish from reality. In dim light, drapes blowing at the window or shadows from street lamps may seem scary. Nightlights in the room, halls, and bathroom, and reflector tape to clearly identify doorways may help banish ghosts and imagined robbers.

The authors advise numerous safety precautions: bedrails, locks on windows and doors, safety gates on stairs, restricted access to the kitchen stove. Sleeping pills may be useful, but they have important drawbacks, the authors note, making falls more likely should the person get out of bed at night, and possibly causing daytime sedation.

Although the authors do not specifically address light exposure in elderly persons, sleep specialists often recommend late afternoon or early evening exposure to bright light, either by going outdoors or sitting in front of a daylight-equivalent artificial light source. Bright lights may help a person to stay up until the same time that others in the household go to bed and to sleep later in the morning. Light also may play a role in regulating moods.