Insomnia is defined as repeated difficulty with sleep initiation, maintenance,consolidation, or quality that occurs despite adequate time and opportunity forsleep and that results in some form of daytime impairment. Specific criteriavary, but common ones include taking longer than 30 minutes to fall asleep,staying asleep for less than 6 hours, waking more than 3 times a night, orexperiencing sleep that is chronically no restorative or poor in quality.Approximately one third of adults report some difficulty falling asleep and/orstaying asleep during the previous 12 months, with 17% reporting this problemas a significant one. From 9-12% experience daytime symptoms, 15% aredissatisfied with their sleep, and 6-10% meets the diagnostic criteria ofinsomnia syndrome.Insomnia is more prevalent in women; middle-aged or older adults; shiftworkers; and patients with medical and psychiatric diseases. In young adults,difficulties of sleep initiation are more common; in middle-aged and older adults,problems of maintaining sleep are more common.As many as 95% of Americans have reported an episode of insomnia at somepoint during their lives. The 2008 update to the American Academy of SleepMedicine (AASM) guideline for the evaluation and management of chronicinsomnia calls insomnia an important public health issue.Acute and chronic insomniaInsomnia is usually a transient or short-term condition. In some cases, however,insomnia can become chronic.Acute insomnia lasts up to 1 month. It is often referred to as adjustmentinsomnia because it most often occurs in the context of an acute situationalstress, such as a new job or an upcoming deadline or examination. This insomniatypically resolves when the stressor is no longer present or the individual adaptsto the stressor.However, transient insomnia often recurs when new or similar stresses arise inthe patient’s life. Transient insomnia lasts for less than 1 week and can becaused by another disorder, changes in the sleep environment, stress, or severedepression.Chronic insomnia lasting more than 1 month can be associated with a widevariety of medical and psychiatric conditions and typically involves conditionedsleep difficulty. However, it is believed to occur primarily in patients with anunderlying predisposition to insomnia (see Pathophysiology). The differentsubtypes of chronic insomnia are described in Etiology.
Chronic insomnia has numerous health consequences (see Prognosis). Forexample, patients with insomnia demonstrate slower responses to challengingreaction-time tasks. Moreover, patients with chronic insomnia report reducedquality of life, comparable to that experienced by patients with such conditionsas diabetes, arthritis, and heart disease. Quality of life improves withtreatment but still does not reach the level seen in the general population.In addition, chronic insomnia is associated with impaired occupational and socialperformance and an absenteeism rate that is 10-fold greater than controls.Furthermore, insomnia is associated with higher health care use, including a 2-fold higher frequency of hospitalizations and office visits. In primary caremedicine, approximately 30% of patients report significant sleep disturbances.Associated problemsDespite inadequate sleep, many patients with insomnia do not complain ofexcessive daytime sleepiness, such as involuntary episodes of drowsiness inboring, monotonous, nonstimulating situations. However, they do complain offeeling tired and fatigued, with poor concentration. This may be related to aphysiologic state of hyperarousal (see Pathophysiology). In fact, despite notgetting adequate sleep, patients with insomnia often have difficulty fallingasleep even for daytime naps.Insomnia can also be a risk factor for depression and a symptom of a number ofmedical, psychiatric, and sleep disorders. In fact, insomnia appears to bepredictive of a number of disorders, including depression, anxiety, alcoholdependence, drug dependence, and suicide. The annual cost of insomnia is notinconsequential, with the estimated annual costs for insomnia being $12 billionfor health care and $2 billion for sleep-promoting agents.In 2005, the National Institutes of Health held a State of the ScienceConference on the Manifestations of Chronic Insomnia in Adults. Thisconference focused on the definition, classification, etiology, prevalence, riskfactors, consequences, comorbidities, public health consequences, and availabletreatments and evidence of efficacy. A summary of this conference can beobtained at the NIH Consensus Development Program Web site.It had been widely believed that most cases of chronic insomnia are secondaryto another medical or psychiatric condition and can be addressed by effectivetreatment of that underlying condition. In fact, insomnia often persists despitetreatment of the primary condition, and in certain cases, persistence ofinsomnia can increase the risk of relapse of the primary condition. Thus,clinicians need to understand that insomnia is a condition in its own right that
requires prompt recognition and treatment to prevent morbidity and improvepatients’ quality of life.The conference report concluded, based on review of the literature and thepanel experts, that the limited understanding of the mechanistic pathwaysprecludes drawing firm conclusions about the nature of the associationsbetween other conditions and insomnia, or the directions of causality.Furthermore, the conference members expressed concern that the termsecondary insomnia may promote undertreatment. Therefore, they proposed theterm comorbid insomnia.EvaluationEvaluation of insomnia primarily comes from a detailed clinical history thatincludes a medical, psychiatric, and sleep history. The sleep history shouldelucidate the type of insomnia (eg, sleep initiation, sleep maintenance), itsduration (transient, acute, or chronic), and its course (recurrent, persistent), aswell as exacerbating and alleviating factors. In addition, the clinician shouldelicit a typical sleep schedule and a complete history of alcohol use, drug use,and intake of caffeinated beverages.The sleep diary is essential for insomnia evaluation; its duration should be for 1-2 weeks. The diary is useful to document initial insomnia severity and to identifybehavioral and scheduling factors. Also, a thorough psychological evaluationneeds to include suspected psychiatric disorders.The role of actigraphy in insomnia evaluation is not well established yet. In thecurrent sleep research field, actigraphy is useful to evaluate circadian rhythmdisorders. Polysomnography is not recommended for the evaluation of insomniaunless there is suspected underlying sleep apnea, paradoxical insomnia, orparasomnia.A patients report of insomnia is nonspecific and can encompass a variety ofconcerns, including difficulty falling asleep, awakening early or easily, problemswith returning to sleep after awakening, or a general poor quality of sleep.Therefore, the clinician must determine what the patient means by “insomnia.”For insomnia to be considered a disorder, it should be accompanied by daytimetiredness, loss of concentration, irritability, worries about sleep, loss ofmotivation, or other evidence of daytime impairment that is associated with thesleep difficulty (see Clinical Presentation).The definition of primary (psychophysiologic) insomnia should meet the one ofthe following 2 conditions: (1) the patient has no current or past history of amental or psychiatric disorder or (2) if the patient does have such a history,
the temporal course of the insomnia shows some independence from thetemporal course of the mental or psychiatric condition.ManagementManagement of insomnia may involve further challenges. If sleep difficulties arenot the presenting complaint, there is often too little time to address them atan office visit.Physicians receive very little training in medical school on sleep disorders andtheir impact on patients’ overall health and quality of life. In fact, mostproviders rate their knowledge of sleep medicine as only fair. Finally, manyproviders are not aware of the safety issues; knowledgeable of the efficacy ofcognitive-behavioral and pharmacologic therapies; or able to determine when apatient should be referred to a sleep medicine specialist.The management of insomnia varies depending on the underlying etiology. If thepatient has a medical, neurologic, psychiatric, or sleep disorder, treatment isdirected at the disorder. Even when comorbid causes of insomnia (ie, medical,psychiatric) are treated, however, variable degrees of insomnia can persist thatrequire additional interventions. In such cases, patients can benefit fromcognitive-behavioral therapy (CBT)] and a short course of a sedative-hypnotic ormelatonin receptor agonist (see Treatment).Primary insomnia is a diagnosis of exclusion. Thus, the differential diagnosis ofprimary insomnia requires ruling out several other conditions, including medical,psychiatric, or circadian-rhythm disorders (eg, delayed sleep-phase syndrome)or other sleep-related disorders, such as periodic limb movement disorder orrestless-legs syndrome. The treatment of primary insomnia begins witheducation about the sleep problem and appropriate sleep hygiene measures. CBTis now considered the most appropriate treatment for patients with primaryinsomnia