An Overview of Sleep Disorders in the Older Patient
Sleep and Aging
Individuals require less sleep as they get older. Sleep in the elderly also tends to be more fragmented, with a longer time required to fall asleep, which in turn results in reduced sleep efficiency. In addition to the reduced efficiency, sleep in older persons also tends to be lighter with increased time spent in stages 1 and 2 sleep and a reduced proportion of slow-wave (stages 3 and 4) sleep. The proportion of time spent in rapid eye movement (REM) sleep is decreased, along with a decrease in REM sleep latency.
Multiple sleep latency tests (MSLTs) indicate that the elderly often experience significant daytime sleepiness, suggesting that they may require more sleep than they can obtain.3 Many older persons spend a considerable portion of the night awake in bed. Older persons tend to go to sleep earlier in the evening and awaken earlier in the morning. Early morning wakening is a common complaint. Daytime napping may also result in delayed sleep onset and a further decrease in the duration of nighttime sleep.
Sleep in Dementia
Dementia is associated with disturbances in sleep. Poor sleep is one of the primary reasons for institutionalization, as patients wake up in a confused and agitated state during the night.4 Patients with dementia have lower sleep efficiency, increased number of nocturnal awakenings, and increased proportion of stage 1 sleep. Some studies have also found a decrease in the proportion of REM and slow-wave sleep.5 The presence of comorbid depression complicates the situation even further.
Sleep fragmentation at night is also accompanied by fragmentation of wakefulness during the day, and patients often fail to remain continuously awake during the day and drift off into sleep.6 The beta-amyloid plaques seen in the brain of patients with Alzheimer’s disease have been found in the suprachiasmatic nucleus, but not in other areas of the hypothalamus, suggesting that there is selective cell death in the endogenous circadian pacemaker that would affect circadian rhythms.7 Among persons with dementia, those with severe sleep apnea have significantly more cognitive impairment than those with mild or no apnea.
Insomnia, that is, difficulty falling asleep, remaining asleep, or the belief that one is not getting enough sleep, may be seen in as many as 35% of community samples.8 The Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) criteria to diagnose insomnia are given in Table I. The causes of insomnia include medical, psychiatric, psychological, environmental, and behavioral causes, in addition to drugs and toxins. Primary insomnia, without any obvious medical or psychiatric precipitating cause, is relatively rare. Insomnia in the elderly is invariably multifactorial.
Several medical conditions can commonly cause sleep difficulties, including pain disorders (eg, fibromyalgia), neurodegenerative disorders (eg, parkinsonism, Huntington’s disease), pulmonary disorders (eg, asthma, cough), dermatologic disorders (eg, severe pruritus), and dementia. Pain and discomfort may delay sleep onset and shorten duration of sleep. Depression is associated with early morning awakening but may also cause difficulty with initiating sleep.
Difficulty with initiating sleep is also seen in anxiety states. Patients with schizophrenia may suffer increased sleep fragmentation, which improves following treatment. Drugs may cause insomnia, daytime sleepiness, or both. Persons may sometimes develop “psychophysiological” insomnia, where the belief that one will not be able to fall asleep becomes self- fulfilling. This may be treated with biofeedback, that is, progressive relaxation of self-hypnosis.9 Poor sleep habits are a very common cause of sleep disruption. Excess napping during the day and excess caffeine intake can impair sleep. Alcohol consumption in the evening prevents deep sleep and increases arousals during the latter part of the night. Excess time spent awake in bed can also cause conditioned wakefulness. Environmental factors such as excess heat, cold, noise, or light will also affect sleep. Common causes of insomnia are enumerated in Table II.
Circadian Rhythm Disorders
Many physiological systems like hormone secretion, blood pressure, body temperature, and the sleep-wake cycle observe a circadian rhythm, with a period of approximately 24 hours. Circadian rhythm disturbances occur when desynchrony develops between the endogenous circadian pacemaker in the suprachiasmatic nucleus of the anterior hypothalamus and exogenous environmental demands. The suprachiasmatic nucleus deteriorates with aging, resulting in progressively weaker and more disrupted circadian rhythms.10 There is also a decrease in the nocturnal secretion of melatonin, which plays a large role in the sleep-wake cycle.11
Circadian rhythmicity is also maintained by external cues such as exposure to bright light, consistent timing of meals, and physical activity. Older persons, especially the institutionalized elderly, spend too little time in daylight. The lack of bright light exposure may result in weak exogenous cues, inadequate to entrain the circadian rhythm of the sleep-wake cycle. Circadian rhythm disorders occur when the nocturnal sleep phase either moves forward, resulting in evening sleepiness and early morning wakening (advanced sleep phase syndrome), or when sleep phase is delayed, causing difficulties falling asleep at night with increased morning sleepiness (delayed sleep phase syndrome). Jetlag is a circadian rhythm disorder that tends to affect older persons more severely than younger persons.
Sleep Disordered Breathing
The prevalence of sleep disordered breathing increases with age, ranging from 5-15% in middle-aged adults to about 24% in the elderly.12 It is characterized by frequent complete (apnea) or partial (hypopnea) cessations in breathing during sleep, lasting 10 or more seconds. This may be due to an upper airway collapse or an inability of the central nervous system to appropriately regulate breathing at the neuronal level. Patients may awaken briefly following each respiratory event and not be aware of it. The resulting sleep fragmentation gives rise to excess daytime sleepiness. It is also associated with reduction in cognitive abilities and with hypertension, obesity, and cardiac arrhythmias. Observation and information from the patient’s bed partner and other family members can help make the diagnosis.
Leg Movement Disorders
Periodic leg movement disorder (PLMD) is characterized by repetitive leg movements during sleep. It is often accompanied by nighttime arousals and changes in sleep architecture. The prevalence increases with age and may affect up to 45% of elderly.13 Periodic leg movement is diagnosed when more than 5 leg movements per hour are detected. A related condition is restless legs syndrome (RLS), which affects between 5% and 15% of older persons. It is often described as a creepy, crawly, burning, tingling, or itching sensation in the legs and feet that increases with drowsiness. Both of these conditions are common with advancing age, renal failure, and iron deficiency.
Parasomnias are a diverse group of behavioral and physiological events that intrude into sleep, occurring during transitions between sleep and waking or from one sleep stage to another. Parasomnias found in older persons include nightmares and nocturnal leg cramps. Bruxism, nocturnal enuresis, and sleeptalking are rare. Other distressing conditions include sleep-related abnormal swallowing syndrome and REM behavior disorder (RBD). Rapid eye movement behavior disorder is characterized by the occurrence of complex motor behaviors during sleep. It typically occurs during the second half of the night when REM sleep is most common. Behaviors include walking, talking, and other vigorous body movements.
Acute RBD is associated with the use of tricyclic antidepressants, fluoxetine, monoamine oxidase inhibitors, and withdrawal from alcohol or sedatives. It is thought to be due to loss of REM sleep-associated muscle atonia, possibly resulting from brainstem cerebrovascular or neurodegenerative disease and the consequent acting out of dreams. Individuals with RBD can occasionally become aggressive and end up injuring themselves and others. Management Physicians need to ask patients about their sleep habits on a regular basis. Taking a good sleep history is the key to making the diagnosis. This should be accompanied by a review of any medical or psychiatric conditions and medication use.
Current American Academy of Sleep Medicine guidelines for the diagnosis and treatment of insomnia recommend focusing on subjective self-report only.14 Sleep diaries are an easy and efficient method for self-reports of sleep. Patients can complete a 2-week sleep diary indicating their usual bedtime and time of arising, a description of the timing, duration, and quality of sleep, use of alcohol and medication, and exercise each day. It is also important to ask the bed partner if the patient snores loudly, behaves abnormally during sleep, or is excessively sleepy during the day.
The routine use of polysomnography is not indicated in the assessment of chronic insomnia. It is indicated when the history suggests that the sleep disturbance may be a function of nocturnal breathing disturbance or PLMD.14 Treatment must be individualized according to patient-specific signs and symptoms, and the management of insomnia invariably necessitates a multidimensional approach.
Ensuring good sleep hygiene is the simplest approach. Reassociating bedtime and the sleeping environment with sleep onset is also very important. Some basic rules of good sleep hygiene are given in Table III. Cognitive behavioral interventions are relaxation-based treatments, sleep restriction therapy, and cognitive therapy. They aim to identify and correct misconceptions about sleep, such as unrealistic expectations about what is an adequate amount, faulty causal attributes, and exaggerations of the consequence of sleepiness. Cognitive therapy has been shown to be as effective as medication in the short term but has better long-term outcomes. Sleep restriction therapy uses sleep deprivation by limiting time spent in bed to the duration of time spent asleep at night.
The basic principles of rational pharmacologic therapy for insomnia are:
• Use of the lowest effective dose • Use of intermittent dosing (2-4 times per week)
• Short-term use (no longer than 3-4 months) • Use of drugs with short elimination half-lives
• Gradual discontinuation of medications • Awareness of rebound insomnia during discontinuation
The use of hypnotic drugs is the mainstay of pharmacologic treatment of insomnia. Both benzodiazepines and nonbenzodiazepine agents are usually efficacious. Benzodiazepine hypnotics with a long elimination half-life tend to produce carryover effects to the next day, including daytime sleepiness and cognitive impairment. The rapidly eliminated benzodiazepines and benzodiazepine-like hypnotic agents cause less carryover effect. Commonly used drugs to treat insomnia are given in Table IV. Serotonin-specific antidepressants like trazodone and paroxetine may help alleviate the sleep disturbance that accompanies depression. There is also evidence that melatonin promotes sleep, even when administered to individuals who suffer from insomnia unrelated to circadian rhythm aberrations.15
Treatment of Other Sleep Disorders
Circadian rhythm disorders. Treatment of advanced sleep phase involves delaying the sleep phase. Older adults should try to go outdoors as late in the day as possible before the sun has set. This late daylight exposure will delay the circadian rhythm, so patients will become sleepy later in the evening and sleep later in the morning. In the absence of sunlight exposure, a bright light box is effective for light exposure during the day.
Sleep apnea. Sleep apnea is treated with nasal continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP). Both devices provide positive pressure to keep the upper airway from collapsing during the night. They also result in reduced snoring, reduced sleepiness in patients, and depressive symptoms in patients and caregivers. Oral appliances such as tongue-retaining devices and mandibular advancement devices can also keep the airway open. Surgical correction is an option. Other treatments include weight loss, not sleeping in the supine position, and avoiding alcohol and hypnotics.
Periodic leg movement disorder/restless legs syndrome. PLMD and RLS can be treated with dopaminergic agents such as levodopa-carbidopa and pergolide. Benzodiazepines and low-potency opiates such as codeine and oxycodone may also be useful. Rapid eye movement behavior disorder. Pharmacologic treatment of RBD is extremely successful using clonazepam in up to 90% of cases.16
Significant numbers of older adults complain of sleep problems. Much of the sleep disturbance is not secondary to aging per se but to chronic medical and psychiatric conditions, medication use, and other sleep disorders like sleep disordered breathing, restless legs syndrome, and REM behavior disorder. All of these conditions are treatable, so it is important for physicians to routinely ask patients about their sleep habits.