Saturday, August 26, 2006

Primary Insomnia

Primary insomnia is sleeplessness that is not attributable to a medical, psychiatric, or environmental cause. The diagnostic criteria for primary insomnia from the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) are as follows:

A) The predominant symptom is difficulty initiating or maintaining sleep or nonrestorative sleep for at least 1 month.

B) The sleep disturbance (or associated daytime fatigue) causes clinically significant distress or impairment in social, occupational, or other important areas of functioning.

C) The sleep disturbance does not occur exclusively during the course of narcolepsy, breathing-related sleep disorder, circadian rhythm sleep disorder, or parasomnia.

D) The disturbance does not occur exclusively during the course of another mental disorder (eg, major depressive disorder, generalized anxiety disorder, delirium).

E) The disturbance is not due to the direct physiologic effects of a substance (eg, drug abuse, medication) or a general medical condition.
The International Classification of Sleep Disorders does not recognize a category of primary insomnia but discusses the following 3 free-standing insomnia subgroups:

1. Psychophysiological insomnia
2. Idiopathic insomnia
3. Sleep state misperception

The disorder is chronic by definition (ie, lasting at least 1 mo).

Causes: Exclusion of other common causes is required to make the diagnosis of primary insomnia.

Medical causes:
1. Chronic pain
2. Primary sleep disorders (eg, sleep apnea, periodic limb movements, restless legs syndrome)
3. Dyspnea from any cause
4. Pregnancy
5. Drug use or withdrawal (eg, selective serotonin reuptake inhibitors, stimulants, antihistamines, caffeine, diet pills, herbal preparations containing ma huang, anticonvulsants, steroids)

Psychiatric and/or psychological causes:
1. Mood disorders (eg, depression, mania)
2. Anxiety disorders (eg, generalized anxiety, panic attacks, obsessive–compulsive disorder)
3. Substance abuse (eg, alcohol or sedative/hypnotic withdrawal)
4. Major life stressors and/or events

Environmental causes:
1. Noise
2. Jet lag or shift work
3. Bedroom too hot or cold

Treatment: Pharmacologic treatment usually provides rapid symptom relief, but controlled studies of long-term treatment have not been conducted.

1. Nonprescription drugs:

The active agent in many of these over-the-counter medications is one of the sedating antihistamines. They are generally safe but have anticholinergic adverse effects such as dry mouth, blurred vision, urinary retention, and confusion in older patients, which can be potentially more serious in patients with dental caries, glaucoma, prostatic enlargement, and dementia (or delirium), respectively.

They are also minimally effective in inducing sleep and may reduce sleep quality. Consequently, discourage patients from using them on a routine basis.

Discourage the use of various herbal preparations (eg, herbal tea) and so-called nutritional substances because of the lack of evidence in their support.

Studies have shown that melatonin may be useful for short-term adaptation to jet lag or other circadian rhythm sleep disorders. The effectiveness of melatonin for chronic insomnia is less clear. A recent study showed that melatonin did not produce any sleep benefit in patients with primary insomnia. Melatonin is sold over the counter and, therefore, is not controlled by the Food and Drug Administration (FDA). The optimal dose and its long-term adverse effects also are not known.

2. Prescription drugs:

Hypnotics and benzodiazepines (BZDs) are the mainstays of short-term treatment of primary insomnia.

Basic principles for rational treatment of insomnia are to use the lowest effective dose, to use intermittent dosing (2-3 nights per wk), to use for short term (2-3 wk at a time), to discontinue after slow taper if the patient has been taking it regularly, and to use agents with short and/or intermediate half-life to minimize daytime sedation.

Pharmacokinetic properties and risk-benefit ratio are the key factors in selecting the most appropriate medication.


Post a Comment

<< Home