With age, the architecture of sleep changes—in fact, most of the change occurs before the age of 60. Sleep is divided into shorter periods interspersed with wakefulness or brief arousals, there is a decrease in total sleep time and in sleep efficiency (the ratio of time asleep to time in bed), and there is less stage 4 (deep) and more stage 1 and 2 (shallow) sleep, without an increase in the proportion of rapid-eye-movement (REM) sleep. This change in sleep architecture is conventionally associated with changes in circadian rhythms with age, such as decreased amplitude and phase length of these rhythms (but see Monk⁽⁴⁾ for a critical review).
Many people adapt to these changes, but others find the altered pattern distressing. Thus the borderline between normal and problematic sleep is blurred, because subjective assessments of sleep quality are not necessarily matched by objective measures (such as polysomnography); consequently the definition of ‘insomnia’ hinges not only on features of night-time sleep, but on impaired functioning in the daytime.

The majority of healthy older people have no complaints about their sleep, but there is a strong association between poor sleep and other health problems, and sleep problems make a material contribution to the impaired quality of life suffered by people with comorbid illness. In a study of patients in primary care,⁽⁵⁾ a positive answer to even one question about sleep (‘do you feel excessively sleepy during the day?’) predicted the quality of life related to physical or mental health problems. Attention to improving sleep in these patients can improve their well-being, but too often the sleep problem is missed in the general assessment of the patient. Impaired sleep can have serious consequences: it is associated with symptoms of anxiety and depression, an increased risk of falls, and diminished memory and cognitive functioning.⁽¹⁾

These include the following:

1 Environmental causes: e.g. a strange bed, noise, cold or heat, or loss of a familiar bed companion (e.g. through bereavement).

2 Physical causes: sleep can be broken by pain, stiffness (e.g. Parkinson’s disease or arthritis), limb movement (restless legs syndrome, periodic movements of sleep), breathlessness (cardiac failure or sleep apnoea), the need to urinate (prostatic disease or urinary tract infection), eating too close to bedtime, or dehydration (e.g. voluntary restriction of fluids to prevent nocturia).

3 Medication: alcohol, especially if taken to relieve anxiety or to assist sleep (since the rapid metabolism of alcohol leads to rebound anxiety and wakefulness), and antidepressants such as selective serotonin reuptake inhibitors (SSRIs) can cause wakefulness or nightmares. Information on the numerous other medications which may impair sleep can be found in Anconi-Israel and Ayalon.⁽¹⁾

4 Psychological causes: for example, anxiety, depression, hypomania, and paranoid illness. Often a sleep problem is triggered initially by a physical cause, but is then maintained by the patient’s anxiety about wakefulness.

5 Sleep in dementia: changes in sleep rhythm in dementia are similar to those of normal old age, but often more severe: daytime drowsiness or napping, difficulty in falling asleep at night, decreases in slow wave sleep and in rapid-eye-movement sleep. However, another common cause of sleep impairment is the use of benzodiazepines or major tranquillizers to treat behaviour disturbances: the patient may end up drugged in the day and wakeful at night. A partial remedy may be to create an overriding diurnal rhythm (e.g. by attendance at day care or a programme of physical activity in the day), together with the minimal use of medication at night. Patients in institutional care are particularly likely to be deprived of the normal cues for circadian rhythms: quiet and darkness at night, bright daylight in the morning, and physical activity in the day. On the other hand sleep time may be strikingly increased in dementia, especially in vascular dementia where it may be part of the apathy that is common in that disease.

The parasomnias that are common in old age are obstructive sleep apnoea (or sleep-disordered breathing); restless legs syndrome and periodic limb movements in sleep; and REM sleep behaviour disorder (RBD). They may range in severity from troublesome to severely disabling, and accurate recognition is important for all of them, because of the consequences both to the patients and to their bed partners if their diagnosis and treatment are missed. Further details can be found in the sources mentioned above,^(1,3) but RBD warrants some further discussion here. This disorder is defined as an ‘intermittent loss of the muscle atonia normally present during REM sleep, and episodes of elaborate motor activity associated with dream mentation’.⁽⁶⁾ Typically, in the early hours the patient (usually male) shouts, thrashes around, and may attack his bed partner, without waking, and without any recollection of the episode when he does wake later. The importance of this condition lies in the fact that it is very distressing, and possibly dangerous, for the bed partner; it can often be treated effectively (with clonazepam); and it is strongly associated with the development (sometimes after a very long latent period, of a decade or more) of neurodegenerative disease—especially Lewy body dementia, Parkinson’s disease, or multisystem atrophy—the alphasynucleopathies.^(6,7)

Starting medication for any condition ought to be treated as the test of a hypothesis. There should be a plan, shared with the patient, setting out the following: