Sleep in the Elderly Stephanie A Silberman Ph

Sleep in the Elderly Stephanie A. Silberman, Ph. D. Sleep Disorders Institute

Normal Aging In the U. S. the average life expectancy is 77 years old. 80% of U. S. residents now live to be at least 65. Fastest growing segment of population is 85 years & older. There are neurological, physiological, and CNS changes in the elderly Decline in slow-wave sleep may occur at a chronological age far earlier than most age-related declines in other biological functions.

Neurology of Aging Cognitive impairment of normal elderly is often termed “benign forgetfulness of senescence” or “ageassociated memory impairment. ” On tests of cognitive functioning, the elderly show decreased capacity to learn new information and in central processing of information. On the WAIS, the performance scale declines more rapidly than the verbal tests. Past and immediate memory remain relatively intact until the mid-70 s, but recent memory is impaired. Reaction time to simple and complex stimuli often delayed and there is impairment of motor speed

Physiologic Changes in Old Age Awake Electroencephalography Slowing of the alpha rhythm and increase of fast activities, diffuse slow activity, and focal slow waves. Alpha slowing appears related to decline in mental function, which may be an early stage of progressive dementia of old age. However, studies have not shown clear relationship between intellectual deterioration and EEG slowing. Presence of fast activity in elderly correlates with preserved mental functioning.

Intermittent focal slow waves (aka benign temporal delta transients of the elderly) in the temporal regions (particularly middle and anterior temporal regions on left side) are noted in 17 -59% of healthy elderly individuals. Voltage usually less than 70 uv and these waves do not disrupt background activity. They are attenuated by mental alertness and eye opening and are increased by drowsiness and hyperventilation. They occur as single waves or in pairs but not in rhythmic trains.

Sleep EEG Changes Delta waves during slow-wave sleep (SWS) are reduced in amplitude and incidence. Therefore, scoring of stages III & IV decreases. Reduction of amplitude of delta waves could be related to three factors: 1) reduction of neuronal synchronization in the neocortex 2) alterations of the skull 3) changes in the subarachnoid spaces Some researchers suggest that FREQUENCY, rather than AMPLITUDE, criterion should be used for scoring SWS in elderly individuals. Sleep spindles may show decreased frequency, amount and amplitude.

Cyclic pattern from REM to NREM remains unchanged, but the first cycle may be reduced. Frequent stage shifts occur. Shorter REM latency in first REM period of night may be due to decreased stages III & IV. REM density (# of eye movement bursts per minute of REM sleep) and total REM sleep time are reduced, but the % of REM in relation to total sleep time remains unaltered. Sleep fragmentation & frequent awakenings common increased stage 1. Nighttime sleep of elders usually reported to be decreased (5. 5 -6. 5 hours versus 7. 5 hours TST average of young adults). However, elders often take daytime naps, so 24 -hour TST may not differ significantly from young adults.

Gender Differences in Sleep of Elderly Between the ages of 60 and 70 years, men have more frequent arousals and more decrements in Stage III and IV sleep. Between 60 - 80 years, women spend 9% of TST in slow-wave stage, whereas men spend only 2%. The % of REM do not differ for men and women between 60 -90 years. Although elderly women typically report more sleep complaints than elderly men, a meta-analysis of PSG data showed that older women sleep somewhat better than older men. Some data have suggested that older women have better-preserved SWS than do men.

Menopause may be associated with poor sleep in women due to endocrine effects. Vasmomotor symptoms (hot flashes) result in lower sleep efficiency and higher # of arousals. Nocturia may also cause sleep disturbance in menopausal women. Studies show conflicting results with the use of estrogen replacement therapy, associating it with both better and poorer quality sleep. Elderly women go to bed at earlier times and/or wake up earlier relative to older men.

Changes in the Circadian Rhythm Age dependent chronobiological changes in physiological functions include: body temperature, the endocrine system, and numerous blood constituents. Temporal disorganization of physiology often considered to be the fundamental characteristic of aging process. Integration of circadian rhythms depends on the suprachiasmatic nucleus (SCN) of the anterior hypothalamus. The SCN is known to deteriorate with age, particularly in women, and so alteration of circadian rhythms in aging may reflect deterioration of these brain structures.

Circadian rhythm changes in elderly result from changes in social, including family, interaction. Alterations of daily routine and activities, health needs, and psychosocial factors (e. g. loneliness) affect these interactions. In long-term care facilities, circadian rhythm disturbances may be related to alterations of Zeitgebers (external time cues), such as bedtime, medication time, mealtime, and special institutional regulations re: lights on and off. The effect of chronic illnesses must be considered in explanations of CRD. Study of evolution of sleep shows that the strong monophasic circadian rhythm of youth gives way to a polyphasic ultradian rhythm in old age. Frequent awakenings at night, with reduction of wakefulness, are accompanied by increased daytime naps.

The phase advance tendency in the elderly may be due to age-related changes in the core body temperature. In elderly persons, the amplitude of the temperature rhythm is attenuated and phase advanced. The relationships between the habitual timing of morning awakening and the body temperature nadir vary differentially by age. That is, in addition to their relative phase advance, elderly persons tend to wake up at a time closer to their temperature minimum, a finding similar to that seen in young adult “larks” when compared to “owls. ” This is particularly true for older women. Much of the insomnia due to early morning awakenings seen in human aging reflects not only circadian effects but homeostatic influences as well.

Sleep Complaints in Old Age SLEEP APNEA – Prevalence of snoring increases with age up to age 70 – High age-associated prevalence of sleep apnea Comprehensive series of cross-sectional studies showed that 24% of independently living elderly (over 65 years) population, 33% similarly aged, acute care inpatient population, and 42% of an elderly nursing home population had an apnea index (AI) of 5 or more – Obstructive events predominate – SA shows age dependence; that is, the longer one lives, the more likely one is to develop the condition

SLEEP APNEA (cont. ) Risk Factors and Mechanisms in the Elderly – increased body weight likely predicts sleep apnea at least as powerfully as chronological age – enhanced upper airway collapsibility related to age – overall declines of muscular strength and endurance seen with aging both in skeletal muscles and the genioglossus – diaphragmatic fatigue may occur – hypothyroidism, declining vital capacity, and altered ventilatory control – intrinsic lightening of sleep architecture (decreased SWS and increased sleep fragmentation)

SLEEP APNEA (cont). Foley et al. (1995) conducted a large epidemiologic study of more than 9000 persons over age 65 and found that over 1/2 had sleep complaints including: trouble falling asleep, multiple awakenings, early morning awakening, daytime naps, and tiredness. – These complaints are more common in women than in men and are often associated with respiratory symptoms, depression, nonprescription & prescription medications, poor self-esteem, and physical disabilities. – 33% of men and 19% of women snored. – 13% of men and 4% of women had observed apneas. – No clear relationship found between loud snoring, observed apneas, or daytime sleepiness to hypertension or cardiovascular disease in elders.

INSOMNIA Prevalence of insomnia in the aged varies across studies, but a recent summary suggests a range of 19 - 38%. Foley et al. (1995) reported that 29% of persons over age 65 have difficulty maintaining sleep. Sleep latency problems range from 10 - 37%. Elderly women have a greater probability of sleep complaints and sedative-hypnotic use than elderly men. Insomnia complaints more prevalent in whites and those with depression, pain, and poor health. Medical disease and chronic illness play an important role in the poor sleep of elderly.

INSOMNIA (cont. ) Conditions such as headache, diabetes, and chronic pain have all been shown to differential impact on the sleep of older adults. Respiratory problems (chronic cough, phlegm) are associated with frequent complaints of insomnia. High incidence of depression with insomnia in elderly. – Strong association between persistent insomnia (longer than 1 month) and the risk of major depression. – Late-life spousal bereavement associated with persistent and debilitating complaint of insomnia. Significant association b/w insomnia & dementia. PLMS can also cause symptoms of insomnia.

INSOMNIA (cont). Prevalence of prescription hypnotic medication use in the elderly population is approximately 10 - 16%. – More common in depressed patients. – Higher all-cause and specific-cause mortality associated with regular use of such medication (Kripke et al. , 1998). Nonpharmacological alternatives or adjunctive treatments for late-life insomnia should always be considered. Treatments shown to improve sleep in the elderly: – – – cognitive behavior therapy sleep restriction therapy appropriately timed bright light therapy exercise (including both strength training & aerobic exercise) passive body heating

PERIODIC LIMB MOVEMENTS Little data to confirm prevalence of PLMs in elderly – Kripke et al. (1982) found that 20 - 30% of subjects over 65 years had PLMS. – Ancoli-Israel et al. (1981) reported an incidence of 37% of PLMS in older subjects. PLMs male predominant. Distinctive periodic motor output may be related to cycles (20 to 40 sec) in arterial blood pressure, but supraspinal factors represent another possibility. Deficits in central dopaminergic transmission likely. Unmedicated patients with advanced stage Parkinson’s disease have abundant PLMs. Alteration in glabellar reflex noted in PLMs.

PERIODIC LIMB MOVEMENTS (cont. ) Osteoarthritic changes or disk abnormalities are common in the elderly and may account for some of the high PLMs prevalence in aged. Iron deficiency may be associated with PLMs. – Elderly RLS subjects with serum ferritin levels of lower than 45 mg / ml showed subjective improvement following use of ferrous sulfate. Aged patients did no differ from controls in total iron, suggesting that iron stores may be most critical. – Because iron plays a critical role in the structure of the D 2 receptor, this provides further evidence of the importance of central dopaminergic transmission in the PLMs of old age. The possibility that the presence of PLMs serves as an early indicator of decreased central dopaminergic transmission and incipient basal ganglia deterioration remains a plausible hypothesis.

DEMENTIA CNS degeneration disorders may cause polyphasic sleep-wake patterns. In demented elderly adults, nocturnal agitation, night wandering, shouting, & incontinence contribute to a variety of sleep disturbances. – Nocturnal agitation may be caused by many factors, including loss of social Zeitgebers and circadian timekeeping, sleep apnea, REM-related parasomnias, low ambient light, and cold sensitivity. Sleep architecture in demented patients shows lower sleep efficiency, higher stage 1 percentage, and greater frequency of arousals and awakenings. Significant findings with regard to REM sleep.

DEMENTIA (cont. ) Role of acetylcholine and its precursors in the induction of REM sleep shown in human and animal studies. Alzheimer’s Disease (AD) characterized by reduced levels of choline acetyltransferase. Some studies indicate decreased REM sleep as a function of TST. Positive relationships b/w higher psychometric test performance and higher REM sleep amounts have been reported. Many demented patients “sundown” during the evening hours or during the night. Sundowning often considered to represent nocturnal delirium.

DEMENTIA (cont. ) Severity of dementia correlated with extent of sleep disruption at night. Onset of delirium may be associated with malnutrition, use of physical restraints, insertion of a bladder catheter, addition of 4 or more medications, and any iatrogenic events (infections, pulmonary embolism, falls, etc. ). Several sleep-specific or chronobiologically based causes postulated to underlie sundowning: – Agitation during nocturnal hours & arising from sleep might be suggestive of REM dyscontrol mechanisms or sleep interruption as an underlying cause. – Agitation during early evening hours not preceded by sleep might be more suggestive of the influence of chronobiological mechanisms.

DEMENTIA (cont. ) REM Dyscontrol – Awakening out of REM sleep in states of delirium with fixed ideas of an everyday (not bizarre) nature. – Substantial number of idiopathic REM Behavior Disorder (RBD) patients have been shown to later develop PD. – Known connections b/w basal ganglia outputs (globus pallidus & substantia nigra), known to deteriorate in PD, and brainstem centers known to modulate REM sleep atonia, have substantial functional impact upon state-dependent motor control in a variety of neurodegenerative conditions. Forced Awakening from Sleep – Demented patients who are awakened frequently during sleep are the most agitated. – Environmental noise within nursing homes also considered a major disruptive influence on sleep. Resident in nursing home is exposed on average to 32 noise events per night in excess of 60 decibels.

DAYTIME SLEEPINESS Sleepiness during the day is not an inevitable component of aging. Studies of successful aging (defined as absence of sleep disorders, psychiatric illness and medical disease) show that elderly people may incur no deficits in daytime alertness on MSLT. – Studies also show that older people are far more likely than younger persons to use both OTC and prescription medication to maintain daytime alertness and are more likely to believe that it is normal to feel sleepy during the day. – In the Cardiovascular Health Study (n = 4500), sleepiness was associated with a greater # of nighttime awakenings, nocturnal symptoms of sleep apnea, depression, presence of congestive heart failure, use of digitalis and diuretics, & limitations in mobility. Within men, sleepiness associated with lower cognitive functioning & certain measures of central obesity. In women, reduced daily exercise & nasal congestion are important factors.