Approximately one third of American adults report that they have sleep problems, and nearly one half of persons with insomnia consider the difficulty to be serious.^1–3 Not only does insomnia cause daytime drowsiness, it may impair quality of life in other ways; poor sleepers have been found to receive fewer promotions, to have increased rates of absenteeism and to demonstrate poor productivity.^4,5 Also, the risk of motor vehicle crashes is increased in this group because of fatigue.⁶

Transient, or intermittent, insomnia lasts only a few days and is usually related to identifiable factors such as acute medical illness, changes in the sleeping environment, self-medication, jet lag and acute or recurring stress from work problems, concerns about health, marital strife, etc. In most cases, this type of insomnia can be relieved with appropriate attention to the inciting stimulus. Chronic insomnia is best defined as the subjective experience of an inadequate quantity or quality of sleep that has persisted for at least one month.^7,8

Chronic insomnia is more complex than acute transient insomnia, requiring a more directed approach to its identification, etiology and treatment. After establishing the chronicity of the complaint, a differential assessment of chronic insomnia can be made on the basis of whether the patient has difficulty staying asleep as opposed to difficulty falling asleep (Table 1). Because insomnia is essentially a symptom and not a diagnosis, it is important to try to determine the cause of chronic insomnia and not just reflexively treat the patient with sedative-hypnotic medications. It is important to remember that use of sedative-hypnotics may worsen sleep-disordered breathing such as that associated with obstructive sleep apnea.

Natural History of Sleep

Sleep is not simply the absence of wakefulness. Rather, it is a complex state of active and coordinated brain processes. As demonstrated by electroencephalography, sleep progresses in four deepening stages, plus rapid-eye-movement (REM) sleep. The four stages are collectively known as non-REM sleep. Stage 1 is a transitional “drowsy” phase that precedes deeper, more restorative stages. Relative to non-REM sleep, REM sleep is associated with brain activity that resembles wakefulness and is linked to most recallable dreams.

The total amount and composition of sleep change throughout life. With aging, the total amount of sleep shortens: infants and children normally sleep 16 to 20 hours a day, adults sleep seven to eight hours a day and, after age 60, adults sleep approximately 6.5 hours a day.⁹ Delta sleep (stages 3 and 4 sleep), the deepest and most refreshing kind of sleep, diminishes markedly with age.¹⁰ In contrast, early stage 1 sleep, the lightest sleep, increases with age.¹⁰ The threshold for arousal is lowest during stage 1 sleep and highest during delta sleep, a feature that helps explain why sleep in old age becomes more fragmented, with more brief awakenings.¹⁰ There is little decline in REM sleep throughout a person's lifetime.

Even though sleep is shorter in duration, shallower and more fragmented in the elderly, poor sleep is not an inevitable consequence of aging, and elderly persons do not necessarily require less sleep than younger persons. Also, constant daytime drowsiness or early-morning awakening should not be considered normal changes of aging. The fact that older adults sleep less than younger adults⁹ may reflect their ability to sleep, not their need to sleep.

Evaluation of Insomnia

A wide range of disorders should be considered in the search for an underlying cause of chronic insomnia. Several etiologies may exist at the same time. Insomnia may be the effect of prescription or over-the-counter medications,⁷ or of a medical condition.¹¹ In addition, insomnia may represent a prodromal indication of psychiatric illness (particularly depression),¹² a sleep-related breathing disorder such as sleep apnea,^13,14 a movement-related disorder such as restless leg syndrome^15–17 or a circadian rhythm disorder.

MEDICATIONS

A wide variety of medications can affect the sleep-wake cycle (Table 2).¹⁸ Among the most common medications that can disturb sleep are beta-adrenergic blockers, thyroid preparations, corticosteroids, selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, methyldopa (Aldomet), phenytoin (Dilantin) and some chemotherapeutic agents.

Alcohol and stimulants such as nicotine and caffeine may cause poor sleep. While consumption of alcohol before bedtime promotes sleep onset, alcohol tends to shorten total sleep time and can exacerbate other conditions such as gastroesophageal reflux and sleep apnea. Alcohol withdrawal in a heavy drinker may be associated with restlessness or tremor, and sleep disturbance can continue for a prolonged period after an alcoholic has stopped drinking.¹⁹

MEDICAL CONDITIONS

Some of the commonly occurring conditions that can cause insomnia are listed in Table 3. A major cause of sleep disturbance in middle-aged women is the menopause-related “hot flush.” Recent studies indicate that nearly every hot flush promotes an arousal from sleep.²⁰ Insomnia may be a reason for instituting hormone replacement therapy.²¹

Certain medical conditions, such as gastroesophageal reflux disease, chronic obstructive pulmonary disease, peptic ulcer disease, prostatic hypertrophy (resulting in overflow incontinence) and congestive heart failure with associated paroxysmal nocturnal dyspnea, frequently disturb sleep and may be interpreted by the patient as insomnia. Recurrent enuresis may disturb sleep and, in an adult, necessitates a genitourinary work-up for incontinence or urinary tract infection. Patients with chronic pain, such as that resulting from fibromyalgia, may have mood and cognitive disturbances in addition to insomnia and early-morning awakening.²²

PSYCHIATRIC CONDITIONS

A psychiatric disorder, such as depression, is frequently a cause of chronic insomnia, especially in the elderly. The effect of a chronic psychiatric illness often leads a patient to self-medicate, producing even more severe insomnia. Other psychiatric conditions that can cause insomnia include anxiety disorder, panic disorder, mania and acute psychosis.

Conditioned insomnia occurs when the act of going to bed triggers anxiety and the inability to go to sleep. In other words, the patient has been inadvertently trained to stay awake at bedtime. A clue to this disorder may be the patient's ability to readily fall asleep at times when he or she is not focusing on obtaining slumber (i.e., unscheduled naps).

SLEEP-RELATED BREATHING DISORDERS

Common symptoms of sleep apnea are loud snoring, choking or gasping episodes during sleep, and excessive daytime sleepiness that the patient may attribute to poor sleep. Obstructive sleep apnea occurs most often in obese patients and may be associated with hypothyroidism.¹³ It is important to consider the possibility of sleep apnea at an early stage in a patient who reports insomnia or other sleep difficulties. If the suspicion of sleep apnea is high, the patient should be referred for a sleep study. The use of medications that are respiratory suppressants (e.g., all sedative-hypnotic medications) should be avoided if a sleep-related breathing disorder is suspected.

SLEEP-RELATED MOVEMENT DISORDERS

Periodic leg movements during sleep are common in persons over 65 years of age.¹⁵ Although these limb movements are often associated with brief arousals, many patients have no sleep symptoms. When these limb movements are associated with insomnia or daytime sleepiness, periodic limb movement disorder may be diagnosed.

In contrast to patients with periodic leg movement disorder, patients with restless legs syndrome are quick to describe an uncomfortable sensation of the limbs that comes on at rest and is relieved by movement such as walking. This restlessness causes a delay in sleep onset. Periodic leg movement disorder commonly coexists with restless legs syndrome. Renal failure with uremia or iron or folate deficiency sometimes underlies restless legs syndrome.

There is much overlap in the treatment of severe periodic leg movement disorder and restless legs syndrome. Drug therapy usually begins with a dopaminergic agent (Table 4). However, other agents such as benzodiazepines, gabapentin (Neurontin) or opiates should be considered if dopaminergic agents aggravate insomnia, exacerbate nocturnal myoclonus or result in “rebound” leg movements in the early morning.¹⁶ Other common adverse effects of dopaminergic agents include fatigue, stiffness, dyspepsia and sedation.^16,17,23

CIRCADIAN RHYTHM DISORDERS

Chronic insomnia may reflect a disturbance in the normal circadian sleep-wake rhythm. Two common circadian rhythm disturbances are advanced sleep-phase syndrome (early bedtime and early awakening) and delayed sleep-phase syndrome (late bedtime and late awakening). Advanced sleep-phase syndrome may be corrected through exposure to bright light for two hours during the evening, which may shift the body's circadian timing mechanism and delay the onset of sleep until a typical bedtime. In contrast, delayed sleep-phase syndrome may be treated by exposure to bright light in the morning.

A number of companies sell portable home phototherapy products that can be used for circadian rhythm disorders, including jet lag. Typically, the lights used to treat these conditions are full-spectrum or cool-white fluorescent tubes that produce 2,500-lux illumination to the eyes, which is about five times the level of normal indoor lighting. Outdoor light, even on overcast days, provides sufficient illumination, but patients must be committed to scheduling outdoor activities at the times necessary to affect their circadian rhythm disorder.

Treatment

Management of chronic insomnia begins with attempts to identify and treat any underlying causes. There may be more than one cause of insomnia, but the causes may be difficult to identify. Drug therapy may be beneficial for short-term improvement, while behavioral intervention provides more sustained effects. Long-term use of many psychotropic or sedative-hypnotic drugs can cause adverse reactions and may actually impair sleep. Behavioral intervention combined with pharmacologic agents may be more effective than either approach alone.

BEHAVIORAL INTERVENTION

Having the patient keep a sleep diary for two weeks may be helpful. Depending on the findings in the sleep diary, a discussion of sleep hygiene may be beneficial (Table 5). Adopting the practices of good sleep hygiene is often beneficial, whether the patient has primary insomnia or a sleep disturbance related to a medical condition.¹⁸ For example, a randomized, controlled trial demonstrated that moderate-intensity exercise (i.e., low-impact aerobics, brisk walking and stationary cycling) improved self-rated sleep quality in men and women aged 50 to 76 years.²⁴ Behavioral psychologists focus on encouraging the patient to eliminate behavior incompatible with sleep, such as lying in bed and worrying, by instructing the patient to leave the bedroom at these times. Patients can condition themselves to be insomniacs, and treatment focuses on deconditioning the patient from associating the bedroom with a place of restlessness.

DRUG THERAPY

When a medication is prescribed for chronic insomnia, it should be given at the lowest effective dosage and on a short-term basis only (Table 6). Having the patient take the medication intermittently is best, and discontinuation should be accomplished gradually to avoid rebound insomnia.¹

In an elderly patient, a short-acting benzodiazepine or zolpidem (Ambien) is preferable because these agents reduce the likelihood of residual daytime sedation. Although technically not a benzodiazepine, zolpidem appears to act by binding to benzodiazepine receptors. In general, the maximum benzodiazepine dosage used in an elderly patient should be one half that of the usual adult dosage.

A low dosage of a sedating antidepressant, such as trazodone (Desyrel), has an advantage over traditional hypnotics in that it does not depress respiration, an attribute that could be relevant in patients with sleep apnea. Trazodone is widely used, both alone and as a hypnotic, in patients who develop a sleep disturbance while taking a selective serotonin reuptake inhibitor or a monoamine oxidase inhibitor. However, one serious, though uncommon, adverse effect of trazodone is priapism.

While antihistamines with sedative properties may be beneficial in younger patients, the use of antihistamines such as diphenhydraminine (Benadryl) or hydroxyzine (Atarax) is not a good choice in elderly patients because of the potential for anticholinergic side effects such as dizziness and urinary retention. Before sedative medications are prescribed for patients with chronic pain syndromes, it is important to ascertain whether they are receiving adequate pain control.

MELATONIN

Melatonin has been used as a clock-resetting agent and as a hypnotic for noncircadian insomnia.²⁵ The clinical utility of melatonin may be related to its clock-resetting role in disorders such as jet lag and shift work. While some studies have shown that melatonin improves sleep onset, its effects on total sleep are not clear. In some cases, melatonin may even disturb sleep. Melatonin has adverse effects, such as antigonadotropic properties²⁵; it can inhibit ovulation by decreasing luteinizing hormone concentrations.

PATIENTS IN NURSING HOMES

Management of insomnia in an elderly patient in a nursing home is a particularly difficult issue (Table 7). One might make arrangements with the staff to allow the patient to get up and go into the day room if he or she is having difficulty sleeping. Patients should be encouraged to exercise in the daytime, and their rooms should be kept dark in the evening when they are trying to sleep.

Final Comment

It is important to know when to refer a patient for further work-up by a sleep specialist. Polysomnographic evaluation is required in patients suspected of having sleep apnea. Patients should also be referred to a sleep specialist if insomnia is refractory to standard behavioral and pharmacologic therapies or if the patient's medical condition or medications cannot explain the symptom of insomnia.