Definition and Overview
Insomnia is a sleep-wake disorder in which one or more of the following symptoms: difficulty falling asleep (difficulty falling asleep), difficulty maintaining sleep (difficulty maintaining sleep), or waking up earlier than desired (early awakening) appears three or more times a week, persists for more than three months despite sufficient sleep opportunities and environments, and is accompanied by dysfunction during the day.
According to the International Classification of Sleep Disorders, Third Edition (ICSD-3) criteria, it is classified into acute insomnia (less than 3 months) and chronic insomnia (more than 3 months). Epidemiological studies show that approximately 10-15% of adults meet the criteria for chronic insomnia.
Causes and Mechanisms
Insomnia is understood as a 3P model in which predisposing, precipitating, and perpetuating factors interact.
hyperarousal mechanism
The core pathology of insomnia is hyperarousal caused by sympathetic overactivation. In patients with insomnia, high-frequency (beta wave) activity on the brain wave increases even during sleep, and a pattern of high sympathetic nerve activity and low parasympathetic nerve activity is observed in heart rate variability analysis. There is also an increase in cortisol secretion from the hypothalamus-pituitary-adrenal axis (HPA axis).
Main Causes and Risk Factors
- Psychological factors: Stress, anxiety, and depression are the most common triggers.
- Autonomic dysfunction: Sympathetic overactivation interferes with initiating and maintaining sleep.
- Sleep apnea: Repeated cessation of breathing during sleep causes awakening.
- Restless Legs Syndrome: Difficulty falling asleep due to unpleasant sensations in the legs.
- Circadian rhythm disruption: Shift work, jet lag, and irregular sleep schedules disrupt our internal clock.
- Drugs and substances: Caffeine, alcohol, steroids, some antihypertensive drugs, beta blockers, etc. interfere with sleep.
- Underlying diseases: Chronic pain, hyperthyroidism, gastroesophageal reflux disease, chronic obstructive pulmonary disease, etc., interfere with sleep.
- Age: The prevalence of insomnia increases in older people due to changes in sleep structure.
symptoms
nighttime symptoms
- I can't fall asleep for more than 30 minutes after lying down in bed.
- It takes more than 30 minutes to fall asleep again after waking up.
- Waking up more than 30 minutes earlier than desired wake-up time and not being able to fall asleep again.
- Even though you get enough sleep, you don't feel like you've slept (non-restorative sleep).
Daytime symptoms
A diagnosis of insomnia must be accompanied by nighttime sleep problems and daytime dysfunction.
- Fatigue or lethargy persists.
- Concentration, memory, and attention decrease.
- Mood changes, irritability, and depression appear.
- The risk of traffic accidents and work mistakes due to drowsiness increases.
- It may be accompanied by physical symptoms such as headaches, indigestion, and increased muscle tension.
diagnosis
Diagnostic criteria
The nature, frequency (more than 3 times a week), duration (more than 3 months), and presence of daytime dysfunction are assessed through history taking.
sleep diary
Sleep patterns are objectively identified by recording bedtime, wake-up time, sleep latency, and number of nighttime awakenings every day for two weeks.
sleep survey tool
Pittsburgh Sleep Quality Index (PSQI) and Insomnia Severity Index (ISI) are used to evaluate symptoms.
polysomnography
It is performed when other sleep disorders such as sleep apnea, restless legs syndrome, and periodic limb movement disorder are suspected. It is not recommended as a primary diagnostic test for simple insomnia.
Autonomic function test
Heart rate variability (HRV) analysis can be used to evaluate the state of autonomic nervous system balance during sleep-wake transition. Once a pattern of sympathetic nerve hyperactivation is confirmed, it is used to establish an autonomic nerve-based insomnia treatment plan.
treatment
Cognitive Behavioral Therapy (CBT-I)
It is a multicomponent treatment that includes sleep restriction therapy, stimulus control therapy, relaxation training, sleep hygiene education, and cognitive restructuring. The American College of Physicians (ACP), American Academy of Sleep Medicine (AASM), and European Society for Sleep Research (ESRS) guidelines all recommend CBT-I as the first-line treatment for chronic insomnia.
Sleep restriction therapy increases sleep efficiency by limiting time in bed to match actual sleep time. When sleep efficiency improves to 85% or more, increase bedtime by 15 to 30 minutes.
Stimulus control therapy strengthens the connection between bed and sleep by preventing the bed from being used for activities other than sleep and sex.
medication
Drug treatment is generally used short-term (within 2 to 4 weeks) or concurrently in the early stages of starting CBT-I.
- Benzodiazepine receptor agonists (Z-drugs): zolpidem, eszopiclone, etc. are used. Short-term use is recommended due to the risk of dependence and tolerance.
- Sleep-wake transition regulator: Orexin receptor blockers (suvorexant) have a low dependence rate due to their mechanism of suppressing wake signals.
- Melatonin receptor agonists: Useful when accompanied by circadian rhythm disorders.
- Low-dose antidepressants: Used for insomnia accompanying depression. Low doses of doxepin are effective in treating sleep maintenance disorders.
autonomic nerve treatment
For insomnia caused by sympathetic nerve hyperactivation, approaches to lower sympathetic nerve activity are attempted through stellate ganglion blockade or transcranial magnetic stimulation (TMS). Parasympathetic nerve activation techniques such as relaxation training, meditation, and deep breathing are also used as an auxiliary method.
sleep hygiene
Sleep hygiene is a code of conduct for regular, quality sleep.
sleep environment
- Maintain the bedroom temperature between 18 and 20 degrees.
- Make the bedroom dark and quiet.
- The bed is used only for sleeping.
sleep habits
- Go to bed and wake up at a certain time every day (including weekends).
- Turn off your smartphone, TV, and computer screen one hour before bedtime.
- Naptime is limited to 20 to 30 minutes and before 3 p.m.
- Avoid consuming caffeine (coffee, green tea, energy drinks) after 2 p.m.
- If you can't fall asleep for more than 30 minutes in bed, get up and do boring activities, then lie down again when you feel sleepy.
exercise
Regular aerobic exercise improves sleep quality and duration. However, vigorous exercise within 4 hours of bedtime may stimulate the sympathetic nerves and interfere with sleep.
Progress and prognosis
Short-term insomnia often improves when the cause of stress is resolved. Chronic insomnia rarely recovers spontaneously and tends to persist for years without treatment.
CBT-I has the advantage of maintaining its effectiveness even after treatment ends. Drug treatment is effective while taking it, but often relapses occur after discontinuation, so combination with CBT-I is recommended.
If chronic insomnia is left untreated, the risk of various complications such as depression, anxiety disorder, cardiovascular disease, and diabetes increases.