Although sleep can be variable in the elderly, there are common trends in sleep architecture with advancing age. Elderly patients have earlier sleep onset and morning awakening times than do persons in early adulthood. With advancing age, normal rapid eye movement (REM) latency shortens with phase advancement of the sleep cycle. This is probably secondary to weakened slow-wave sleep (SWS) in the first one-third of the night. In the elderly, the amount of SWS is markedly suppressed based on the reduction in slow-wave amplitude rather than a decrease in delta wave abundance (5,6). The exact age of decline of delta activity is unknown but is believed to begin as early as young adulthood (6). Despite this phase advancement, the amount of stage 1 sleep increases, while REM sleep stays approximately the same.

It is still uncertain whether elderly patients have similar sleep needs or a reduction in the need for sleep compared with younger adults. Although nocturnal sleep may be more fragmented, the need for sleep may be met by napping. Naps become more prominent in the elderly. The daytime naps taken by elderly individuals also show relatively low amounts of SWS and are more fragmented than those of younger subjects. Many normal elderly patients perceive these normal changes in sleep physiology as insomnia. If patients do not complain of excessive daytime sleepiness (EDS), then most of these patients can be reassured that their sleep patterns are normal.

Sleep architecture is also altered secondary to an increase in the number of spontaneous awakenings. Sleep lightens behaviorally, secondary to a lowered threshold for awakening stimuli. In addition, central and obstructive apneas and periodic limb movements of sleep (PLMS) increase in frequency with advancing age, which further disrupts consolidation of sleep. The higher incidence of sleep disorders in males may be part of the underlying factor for slightly poorer sleep efficiency in elderly males.

Several other factors also act as contributors to decreased sleep in older patients. These factors include inactivity, hypnotic and alcohol use, over-the-counter and
prescribed medications, illness, decreased light exposure and loss of social cues, and bereavement. Neurodegenerative changes such as Alzheimer’s disease also become more prominent in the elderly.

It is important to differentiate fatigue from EDS in the elderly. Differentiation of EDS and fatigue is important because the causes of EDS are primarily sleep disorders, and fatigue may be induced by sleep disorders or intrinsic medical, neurologic, and psychiatric conditions (7). Prevalence rates for EDS in the elderly have been estimated to be ≥15% (8). Psychiatric disorders, including depression, bipolar disorder, and drug dependency, and medical conditions, including cardiopulmonary dysfunction, endorgan dysfunction, and neurodegenerative disease, can all present not only with fatigue but also contribute to sleep disorders. It may be difficult to differentiate the primary factor, but treatment of the underlying medical or psychiatric condition will often improve complaints of both fatigue and EDS. Even healthy elderly patients tend to have more EDS compared with middle-aged adults. The alteration of sleep physiology and higher prevalence of many sleep disorders will increase the probability of EDS with advancing age.

Although rare, there have been case reports of initial diagnosis of narcolepsy in the elderly (9). This may be related to narcolepsy being overlooked when patients present with EDS at a younger age. Many patients will continue to have symptoms even if diagnosed at an earlier age. In addition, sleep disorders, such as obstructive sleep apnea (OSA), periodic leg movements (PLMs), and other parasomnias will have associated arousals. These conditions typically increase with advancing age and are discussed below based on their presentations.

Elderly patients with EDS require close scrutiny not only of their presenting symptoms but also of concurrent medications. Elderly patients will develop more frequent medical problems and will subsequently be placed on increasing numbers of medications. Both prescription and nonprescription medications may make it more difficult to differentiate between EDS and fatigue. Although many medications may cause EDS, the benefit for the patient typically will outweigh the adverse effects. Since most elderly are on multiple medications, the assessment of current medications is paramount in the determination of EDS with advancing age. Obviously, sedative-hypnotics such as benzodiazepines (especially those with a long duration of action) may increase daytime sleepiness and may also exacerbate underlying sleep apnea. Even if patients are not prescribed sedative-hypnotics, many elderly patients will self-medicate with alcohol. Antidepressants may suppress REM sleep and impair daytime performance due to EDS. Although tricyclic antidepressants may improve sleep continuity, EDS is a common complaint in the elderly utilizing tricyclic antidepressants possibly secondary to suppression of REM sleep. Aspirin may have a net effect on EDS by increasing stage 2 sleep, decreasing SWS, and decreasing overall sleep efficiency. Beta-adrenergic antagonists, such as propranolol, may result in difficulty falling asleep and more frequent awakenings. Histamine-1 antagonists are frequently associated with drowsiness due to inhibition of N-methyltransferase and the blockage of central histaminergic receptors. On the contrary, histamine-2 antagonists, including cimetidine and ranitidine, usually have no significant effects on sleep. Substances that increase nocturnal wake time with resultant EDS include beta-adrenergic blockers, stimulants, caffeine, and diuretics. Other medications commonly used in the elderly that may cause EDS include antiepileptic drugs and antipsychotic agents (7,10).

In the past, medical treatment of EDS in elderly patients was more problematic due to the risk for hypertension associated with the use of stimulants. The recent approval of modafinil for narcolepsy has provided a much safer means of treating EDS in both young and older populations. In the near future, modafinil may acquire Food and Drug Administration approval for use in fatigue and other related disorders, potentially providing a means to improve EDS in patients without treatable underlying medical or psychiatric conditions.

The average total sleep time increases slightly in the elderly. Nonetheless, elderly patients are more likely to be concerned with difficulty falling asleep. The prevalence of insomnia in the elderly varies between 19.0% and 38.4% with difficulty falling asleep ranging from 10% to 36.7% (11,12). Women are often more likely than men to have difficulties with insomnia. It has been estimated that nearly 30% of elderly patients have difficulty with maintenance of sleep (11). Current research points to both physiologic and lifestyle changes in the elderly. Patients produce less melatonin and growth hormone with advancing age. Changes in core body temperature also likely play a role. Environmental factors including a reduction of exposure to natural light and reduction of exercise may exacerbate sleep difficulties. Frequent nocturnal arousals result in EDS. To reduce EDS, elderly patients frequently take naps. These naps often further exacerbate sleep disturbances in the elderly, secondary to difficulty with falling asleep at night, resulting in a revolving cycle.

Difficulty with maintenance of sleep is also commonly related to medical or psychiatric illness. When patients have concerns with difficulty falling asleep or maintaining sleep, it is important to assess for other possible precipitating disease processes (Table 12-1). Patients without medical and psychiatric illness have lower sleep complaints than do patients with concurrent medical illness (13,14,15 and 16).
Unfortunately, the frequency of medical and psychiatric illness increases with advancing age.

Cardiopulmonary conditions often contribute significantly to sleep disturbances in the elderly. Paroxysmal nocturnal dyspnea may produce shortness of breath with resultant insomnia. Ischemic heart disease may produce nocturnal angina in approximately 10% of cases, particularly during REM sleep. Because OSA also becomes more prevalent, elderly patients may have increased frequency and severity of nocturnal hypoxemia (17). Cheynes—Stokes breathing is a prominent cause of arousals and is present in approximately 50% of patients with congestive heart failure (CHF). Chronic lung disease contributes to nocturnal hypoxemia secondary to increased ventilation requirements and sleep-related factors that decrease ventilatory function. Decreased accessory muscle activity during REM sleep may cause diminished ventilation and resultant hypoxemia. Management is difficult and often requires concurrent use of medications and positive airway pressure. Positive airway pressure may not only prevent hypoxemia and arousals due to apneic episodes, but also may relieve chronic respiratory muscle fatigue (17).

Other medical disease processes that produce disruption of normal sleep physiology include gastroesophageal reflux disease and rheumatologic disease, such as arthritis and fibromyalgia. Chronic renal failure also increases in frequency with advancing age. Polysomnography (PSG) in chronic renal failure has demonstrated reduced SWS, poor sleep efficiency with increased arousals, increased restless legs and periodic limb movements of sleep (PLMS) due to iron-deficiency anemia, and significantly increased incidence of OSA. In chronic renal failure, increased frequency and severity of obstructive apneas may be due to fluid retention and upper-airway edema, and central apneas may be more frequent secondary to metabolic acidosis (17).

Independently, sleep-related disorders must also be considered. The frequency of certain sleep-related disorders increase in frequency with advancing age and common precipitants of nocturnal arousals include nocturia, restless legs syndrome (RLS), PLMS, nocturnal leg cramps, REM behavior disorder (RBD), and sleep-related breathing disorders. Nocturia is a common precipitant of maintenance of sleep disturbances with a prevalence in the elderly of 63% to 72% (4,11). RLS occurs in approximately 5% of the population, but accounts for one-eighth of insomnia (18). It is relatively rare in younger patients, but becomes more common with advancing age. Patients with RLS will have an uncontrollable desire to move limbs secondary to associated paresthesias or dysesthesias that is worse at rest and may be relieved with movement. Most patients with RLS complain of sleep disturbances, including difficulty falling asleep, frequent nocturnal awakenings, and associated EDS. RLS has been associated with several conditions that may be more prevalent with advancing age, including renal insufficiency, uremia, diabetes, iron-deficiency anemia, chronic obstructive pulmonary disease (COPD), diabetes, vitamin B₁₂ and folate deficiency, and peripheral neuropathy. The differential diagnosis in the elderly population includes polyneuropathy, radiculopathy, peripheral vascular disease, and vascular claudication (18,19). Approximately 80% of patients with RLS will have PLMS that may subsequently result in frequent arousals that exacerbate EDS (20).

Elderly patients also tend to have more conditions associated with pain, with increased prevalence with advancing age. Approximately one-third of all pain sufferers have arthritic complaints. Nighttime pain sufferers may lose over 2 hours of sleep per night. Other pain syndromes including headaches, leg cramps, and fibromyalgia may also contribute to disruption of sleep. Nocturnal leg cramps may occur in approximately 15% of the population with increased frequency with advancing age. These cramps may resolve in seconds but occasionally last a few minutes, with common precipitants, including strenuous exercise, fluid and electrolyte disturbances, diabetes, caffeine, and nicotine in the elderly. Disturbance of calcium metabolism and other metabolic dysfunction is suspected (21,22).