DEAR DR. DONOHUE: My 92-year-old mom does not get more than four or five hours of sleep each night. The next day, she feels tired and ends up taking a couple of naps.

Some naps are half an hour, and some are an hour or more. I think she should sleep at least seven hours a night. Some of the residents in her senior apartment complex tell her that as you get older, you do not sleep as much.

She is active and participates in activities in her clubhouse, so she is out and about almost every day. Is it true that when we get older, we do not require as much sleep? – L.M.

ANSWER: Some say that we require less sleep as we age, but others – and they are in the majority – say that’s bunk. Older people’s sleep cycles are not the same as they were in their youth, and insomnia is more common after age 65, but neither of those facts indicates a lessening of the number of needed sleep hours.

At older ages, sleep is interrupted by many awakenings. Older people spend less time in the deep stages of sleep. They often have illnesses that rouse them from sleep. Moving an arthritic joint can produce waves of pain that disrupt sleep. Your mom’s daytime sleepiness is proof that she’s not getting enough nighttime sleep.

Your mother should cut back on her naps. She should not take a nap of longer than 20 minutes. If need be, she should set an alarm to wake her after 20 minutes. She should never nap after 3 p.m. If she feels like she’s going to nod off, she should get up and go to a place where she can interact with others. Even if she feels a bit sleep-deprived by doing this, the routine can reset her sleep cycles within a couple of weeks and give her more sustained nighttime sleep.

At night, if she hasn’t fallen asleep after 20 minutes in bed, she should get up and watch TV, read or listen to the radio until she feels tired. Then she can go back to bed.

If things don’t turn around, she can ask her doctor if she could use a mild sleeping pill to re-establish her sleep pattern. Rozerem is such a drug. It doesn’t create dependency and isn’t a danger for someone her age.

DEAR DR. DONOHUE: I read with interest your column about laxatives. I too was having a problem with constipation, so I purchased a box of Kellogg’s All-Bran Bran Buds and ate a bowlful of it with fresh fruit every day for three days. Then I switched to every other day, and I have been doing just great. I just thought you’d like to know that I did this without bothering a doctor. – M.H.

ANSWER: I like your approach. I don’t know if Bran Buds will work for everyone, and I do know that there are many other fine cereals that contain a good amount of fiber. Others should imitate your prescription for constipation.

The booklet on constipation and laxatives offers other suggestions for this common problem. Readers can obtain a copy by writing: Dr. Donohue – No. 504, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.75 U.S./$6.75 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DEAR DR. DONOHUE: In a recent column, you spoke about a kind of restless leg syndrome that is different from regular restless leg syndrome.

My husband’s legs jump every 15 seconds when he lies down – asleep or awake. The bed shakes. This has been going on for years. Neither of us sleeps well. We need help. Please write about this condition again. – J.F.

ANSWER: That condition is periodic limb movements of sleep. Sometimes it goes hand-in-hand (leg-in-leg?) with restless leg syndrome, and sometimes it exists by itself. The ankles, knees or hips bend and straighten and the movements last up to five seconds and occur every 20 to 40 seconds.

Two Parkinson’s disease medicines – Requip and Mirapex – often can stop the movements.

People with periodic limb movements of sleep should be checked for an iron deficiency. It might underlie this condition, as it can underlie restless leg syndrome.

DEAR DR. DONOHUE: Will you please discuss ketones? What are they, and how do you get rid of them? – M.G.

DEAR DR. DONOHUE: I have diabetes. I have been warned about getting ketones. What are they? – J.K.

ANSWER: Ketones are byproducts of cell metabolism when fat is the primary source of cell energy. In diabetes, blood sugar cannot enter cells. If blood sugar stays high for a long time, the cells have to turn to fat for their energy. It’s an alternative fuel. Ketones are the exhaust products of fat-burning.

Ketones appear in many instances. When dieting, ketones are generated. A diet high in fats can also generate them. So can a fever. An overactive thyroid gland produces ketones.

If ketones are found in the blood or urine on only one occasion, then that’s a transient thing and not a worry. If they are found regularly, then their cause has to be found.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com