What causes insomnia and how to treat it?
Insomnia, which is characterized by difficulty sleeping, is a common health condition that leads to distress from and dissatisfaction with the quality and quantity of sleep. Insomnia is different from purposeful sleep deprivation, as people with insomnia not only want to sleep but might even try to force sleep.
Recent estimates indicate that between 10-20% of individuals with insomnia also experience psychosocial, medical, psychiatric, and underlying sleep disorders. Daytime functioning is affected by both short- and long-term insomnia, while chronic insomnia can cause serious health and social impacts.
Study: Insomnia. Image Credit: Kleber Cordeiro / Shutterstock.com
A new article in the Medical Clinics of North America journal by Eliza L. Sutton MD, of the Department of Medicine, University of Washington evaluates the symptoms of insomnia and its treatment as reported by patients in primary care settings.
Insomnia is categorized by its pattern and duration during the night.
Acute insomnia can be treated by addressing the factors that cause it or sedative-hypnotic medication to prevent the development of chronic insomnia. Comparatively, chronic insomnia can lead to dysfunctional beliefs regarding sleep that include helplessness, hopelessness, and fear of the result of sleep loss.
Insomnia can also be categorized into three types, depending on the timing of its occurrence. These include sleep-onset insomnia, sleep-maintenance insomnia, and terminal insomnia.
Pathophysiology of insomnia and sleep
Sleep consists of two physiological states, which include rapid eye movement (REM) and non-REM (NREM) sleep. During both REM and NREM sleep, the body and brain behave in distinct ways. For example, NREM consists of four stages, where stages 3 and 4 are deeper and known as “slow-wave” sleep.
Sleep disorders in which a person is partially roused from deep sleep or REM sleep to a lighter stage of sleep, or to brief awakening, can present as disrupted sleep (insomnia) or unrefreshing sleep.”
Both wake and sleep states are under homeostatic and circadian control. The internal clock, which governs the circadian rhythm of sleep and wake cycles, can be influenced by genetic and environmental factors. For example, an increase in the time since the last sleep increases the homeostatic drive, while the refreshing quality of sleep decreases it.
The daily pattern of fatigue and alertness, which is also referred to as the ‘chronotype,’ is determined by many genes with polymorphisms. An individual’s chronotype fluctuates during both childhood and adolescence until it ultimately stabilizes by the age of 25.
Insomnia can be caused by the influence of wake-conducive factors hours before sleep. These can include bright light exposure, upright body position, consumption of caffeine, or performing a mentally stimulating activity. Moreover, insomnia can arise from forcing sleep, which can backfire and conversely lead to arousal.
Sleep disorders that present as insomnia
There remains limited information on why insomnia presents as a symptom of other health conditions. Some common sleep disorders that often present as insomnia include restless legs syndrome (RLS), circadian rhythm disorders, and sleep apnea.
RLS is a common disorder with a prevalence of approximately 10%. This condition is most commonly observed in individuals of older age, women, during pregnancy, and those with chronic medical conditions.
Between two- to three-fold higher rates of difficulty staying and falling asleep have been reported by RLS patients as compared to the general population. Periodic limb movements (PLMS) have also been found to have the same prevalence as RLS and cause difficulties in remaining asleep.
Circadian rhythm disorders are characterized by occasional feelings of sleepiness during the 24-hour day and being too awake during other times of the day that do not match the social norm.
Delayed sleep phase syndrome (DSPS) is a type of circadian rhythm disorder in which people have late bedtime and waketimes as compared to others. DSPS is associated with higher rates of smoking, caffeine use, alcohol use, depression, and attention-deficit/hyperactivity disorder (ADHD). Other common circadian rhythm disorders include non-24-hour circadian rhythm disorder and advanced phase sleep syndrome (ASPS).
Obstructive sleep apnea (OSA) can present as insomnia due to brief periods of awakening between sleep. OSA can also coexist with certain types of insomnia, such as psychophysiological insomnia.
OSA is quite common among the general population and is mostly associated with chronic conditions such as obesity and hypertension, with the risk of this condition increasing with greater age and body mass index (BMI). Central sleep apnea (CSA) can also present as insomnia; however, its prevalence is not fully described in the general population.
Both OSA and CSA can co-exist in the same patient. However, CSA can become a problem following continuous positive airway pressure (CPAP) therapy for OSA if it occurs in the same patient.
Evaluation of insomnia
Understanding the medical history of a patient is important for the assessment of insomnia. Questionnaires regarding the severity of insomnia, OSA risk, RLS, and chronotype are commonly used in sleep medicine research and practice. Hallmark features of RLS, circadian rhythm disorder, and sleep apnea must also be examined.
Laboratory work, a physical examination, and sleep testing are not particularly useful in the assessment of insomnia. However, in some cases, polysomnography (PSG) might be useful in the evaluation of insomnia, such as when PLMS or sleep apnea is suspected or when patients have a history of circadian rhythm disorder.
The pharmacotherapy of insomnia relies on 2 general approaches: stimulate a sleep-promoting system (via GABAA or melatonin receptors) or suppress one or more wake-promoting systems (particularly via histamine, acetylcholine, and/or serotonin receptors).”
Ramelteon is a melatonin-receptor agonist that has received approval from the United States Food and Drug Administration (FDA) for the treatment of insomnia. Benzodiazepine (BDZ) receptor agonists, which are also known as Z-drugs, are also helpful in the management of acute and chronic insomnia.
Sleep hygiene is an important non-pharmacological intervention that can help people with insomnia. Cognitive-behavioral therapy for insomnia (CBT-I) has also been reported to be effective for people with insomnia comorbid, primary insomnia, and conditioned insomnia. In fact, CBT-I is more effective than sleep meditation and relaxation therapy.
Dopa agonists or a(2)d ligands are also effective in the treatment of RLS or PMLS. Sleep apnea can be treated by reducing the airway obstruction, with the standard treatment being bilevel positive airway pressure or continuous positive airway pressure (CPAP).
Avoidance of the supine sleep position can also help to reduce sleep apnea. Chronic cases of sleep apnea require surgery for the removal of obstructing tissues.
Circadian rhythm disorders can be treated using a four-fold approach that includes expectation management, chronotherapy, phototherapy, and melatonin supplementation.
Insomnia is a widely prevalent disorder that affects people globally. The severity of this condition differs among people and most often appears alongside other medical conditions and among those of an older age.
The medical history of the patient, along with the existence of any other sleep disorders, must be assessed accurately to conclusively diagnose a patient with insomnia. The two most common approaches to treating insomnia are sleep hygiene maintenance and sedative medications. Certain lifestyle changes can also prevent chronic cases of insomnia.