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Definition of Insomnia Disorder

Insomnia disorder is a sleep disorder characterized by persistent difficulties in falling asleep, staying asleep, or experiencing non-restorative sleep, despite having adequate opportunities for sleep. Individuals with insomnia disorder often struggle with sleep despite having the desire and circumstances to sleep, leading to various daytime impairments.

This disorder can manifest in different ways, including difficulty initiating sleep, frequent awakenings during the night with trouble returning to sleep, or waking up too early in the morning and being unable to go back to sleep. As a result, people with insomnia disorder typically experience fatigue, low energy, mood disturbances, irritability, difficulty concentrating, and impaired performance during waking hours.

Insomnia disorder can be classified based on its duration and frequency. It can be short-term (acute insomnia) or long-lasting (chronic insomnia), and it may occur intermittently or persist for extended periods, usually lasting for at least three nights per week and persisting for at least three months.

There are various causes of insomnia disorder, including stress, anxiety, depression, medical conditions, medications, poor sleep habits, irregular work schedules, or lifestyle factors. Treatment may involve addressing underlying causes, cognitive-behavioral therapy, sleep hygiene practices, and in some cases, prescription medications under the guidance of a healthcare professional.

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History of Insomnia Disorder

Insomnia, or the inability to sleep, has been a recognized condition throughout human history. Its description and understanding have evolved over time, often influenced by prevailing medical and cultural beliefs.

  • Ancient writings from civilizations like Egypt, Greece, and Rome indicate that sleep disturbances were acknowledged and discussed. Early explanations often tied insomnia to supernatural or spiritual causes, attributing it to divine displeasure, evil spirits, or imbalances in bodily fluids.
  • In ancient Greece, Hippocrates, often regarded as the father of medicine, described various sleep-related disorders, including insomnia. He suggested lifestyle changes, such as adjusting diet and physical activity, to help manage sleep difficulties.
  • Throughout the medieval period, explanations for insomnia often blended religious and medical ideas. Treatments involved prayers, herbal remedies, and attempts to balance bodily humors, as per the beliefs of that time.
  • During the Renaissance and Enlightenment eras, medical understanding began to incorporate scientific reasoning. Thomas Willis, a 17th-century physician, studied sleep disorders and proposed physiological explanations, moving away from purely supernatural or spiritual interpretations.
  • The Industrial Revolution and modernization led to changes in work patterns, increased stress, and lifestyle shifts, contributing to the prevalence of insomnia. Medical understanding continued to evolve, with researchers exploring the relationship between psychological factors, such as stress and anxiety, and sleep disturbances.
  • In the 20th century, advancements in psychology and medicine brought about a deeper understanding of sleep disorders, including insomnia. Researchers began to distinguish different types of insomnia and explore its connections to mental health, physical health, and various other factors. Diagnostic criteria were established, leading to the formal recognition of insomnia disorder as a distinct clinical condition.
  • Since then, research into the causes, mechanisms, and treatments for insomnia has continued to advance. Cognitive-behavioral therapies for insomnia (CBT-I) have gained prominence as effective non-pharmacological treatments. Additionally, medications designed to aid sleep have been developed, though their long-term use and effectiveness have been subjects of ongoing study and debate.

Throughout history, the understanding and treatment of insomnia have evolved significantly, reflecting the changing paradigms in medicine, psychology, and societal views on health and wellness. Today, insomnia is recognized as a common sleep disorder with various contributing factors, and there is ongoing research aimed at improving its management and treatment approaches.

DSM-5 Criteria of Insomnia Disorder

The DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition) provides criteria for the diagnosis of insomnia disorder. Here are the criteria for diagnosing insomnia disorder:

  • Difficulty initiating sleep, maintaining sleep, or waking up too early.
  • Difficulty falling asleep despite having the opportunity and desire to sleep.
  • Frequent awakenings during the night, with difficulty returning to sleep.
  • Waking up too early in the morning and being unable to go back to sleep.
  • The sleep disturbance causes significant distress or impairment in social, occupational, educational, academic, behavioral, or other important areas of functioning.
  • The sleep difficulty occurs at least three nights per week and is present for at least three months.
  • The sleep disturbance occurs despite adequate opportunities for sleep.
  • The sleep difficulty is not better explained by another sleep disorder, does not occur exclusively during the course of another sleep disorder (e.g., sleep apnea), and is not due to the direct physiological effects of a substance or a medical condition.

These criteria help clinicians diagnose insomnia disorder by assessing the nature, frequency, duration, and impact of sleep difficulties on an individual’s life. The diagnosis of insomnia disorder involves ruling out other potential causes of sleep disturbances and ensuring that the sleep problems persist despite adequate sleep opportunities.

It’s important to note that a comprehensive evaluation by a healthcare professional is necessary to accurately diagnose and treat insomnia disorder. Treatment approaches may involve behavioral interventions, lifestyle changes, cognitive-behavioral therapy for insomnia (CBT-I), and sometimes medications, depending on the specific circumstances and underlying causes.

Etiology of Insomnia Disorder

Insomnia disorder can arise from a variety of factors, and its causes are often multifaceted, including both psychological and physiological elements. Here are some common factors contributing to the development of insomnia disorder:

Psychological Factors:

Stress, anxiety, depression, and other mental health disorders are significant contributors to insomnia. Racing thoughts, worry, and emotional distress can make it difficult to relax and fall asleep, leading to sleep disturbances.

Poor Sleep Hygiene:

Irregular sleep schedules, engaging in stimulating activities before bedtime (such as using electronic devices), consuming caffeine or nicotine close to bedtime, and an uncomfortable sleep environment can all disrupt sleep patterns.

Medical Conditions:

Chronic pain conditions, asthma, allergies, gastrointestinal issues, neurological disorders, hormonal imbalances (e.g., thyroid problems), and other medical conditions can interfere with sleep and contribute to the development of insomnia.


Certain medications, including some antidepressants, stimulants, medications for high blood pressure, and corticosteroids, can disrupt sleep patterns as a side effect, leading to insomnia.

Lifestyle Factors:

Shift work, jet lag, irregular work hours, or frequent travel across time zones can disrupt the body’s internal clock (circadian rhythm), causing difficulties in falling asleep or maintaining sleep.

Environmental Factors:

Noisy or excessively lit sleep environments, uncomfortable room temperature, and disruptions from external factors (such as a partner’s snoring or household noise) can hinder sleep quality.

Behavioral Patterns:

Certain behaviors or habits, such as napping during the day for extended periods, irregular bedtime routines, or using the bed for activities other than sleep or intimacy, can contribute to insomnia.

Genetic Predisposition:

There may be a genetic component that makes some individuals more susceptible to sleep disorders, including insomnia.

Understanding the specific cause or causes of insomnia in an individual can be complex as it often involves a combination of these factors. Additionally, acute episodes of insomnia can sometimes develop into chronic insomnia if not addressed properly. Management and treatment of insomnia typically involve identifying and addressing the underlying factors contributing to sleep disturbances. This may include lifestyle modifications, improving sleep hygiene, stress management techniques, cognitive-behavioral therapy for insomnia (CBT-I), and sometimes medications, under the guidance of a healthcare professional. Identifying and addressing the root causes are essential in effectively managing and treating insomnia disorder.

Theories related to Insomnia Disorder

Several theories attempt to explain the mechanisms and contributing factors behind insomnia disorder. These theories encompass various aspects of sleep physiology, psychology, and neuroscience. Here are some notable theories related to insomnia disorder:

Hyperarousal Theory:

This theory suggests that individuals with insomnia have heightened physiological and cognitive arousal, making it challenging for them to relax and fall asleep. Increased activity in the brain, elevated heart rate, and heightened cognitive alertness can impede the natural progression into sleep.

Cognitive-Behavioral Model:

This model emphasizes the role of maladaptive thoughts, beliefs, and behaviors about sleep that perpetuate insomnia. Negative thoughts about sleep, excessive worry about not sleeping, and engaging in counterproductive behaviors related to sleep can maintain and exacerbate sleep difficulties.

Stress and Emotional Regulation:

Stressful life events, anxiety, and emotional distress can significantly impact sleep. The inability to switch off thoughts related to stressors, combined with emotional dysregulation, may interfere with the ability to relax and fall asleep.

Homeostatic and Circadian Rhythms:

Insomnia can result from disruptions in the body’s homeostatic sleep drive (the pressure to sleep that accumulates during wakefulness) and circadian rhythms (the body’s internal clock that regulates sleep-wake cycles). Irregular sleep schedules, shift work, and jet lag can disturb these rhythms, contributing to sleep difficulties.

Neurobiological Factors:

Research suggests that alterations in neurotransmitters, particularly those involved in sleep regulation such as serotonin, dopamine, and GABA (gamma-aminobutyric acid), may play a role in insomnia. Imbalances in these neurotransmitters can affect sleep onset, maintenance, and quality.

Sensitivity to Environmental Stimuli:

Individuals with insomnia may have heightened sensitivity to external stimuli, such as noise, light, or temperature variations, making them more susceptible to sleep disturbances.

Genetic Predisposition:

Some evidence suggests a genetic component in the development of insomnia, indicating that certain genetic variations or predispositions may increase susceptibility to sleep disturbances.

These theories often intersect and interact, contributing to the complexity of insomnia disorder. Understanding these theories helps healthcare professionals tailor interventions and treatments to address the specific underlying factors contributing to an individual’s insomnia. Treatment approaches often involve a combination of cognitive-behavioral strategies, lifestyle modifications, and, in some cases, pharmacological interventions to target the multifaceted nature of insomnia.

Risk factors of Insomnia Disorder

Insomnia disorder can develop due to a combination of various risk factors. These factors increase the likelihood of experiencing sleep difficulties. Some common risk factors associated with insomnia disorder include:

Stress and Anxiety:

Persistent stress or anxiety can lead to hyperarousal, making it difficult to relax and fall asleep. Daily worries, work-related stress, or major life events can contribute to the development of insomnia.

Mental Health Conditions:

Conditions such as depression, bipolar disorder, post-traumatic stress disorder (PTSD), and generalized anxiety disorder are often linked with insomnia. The relationship between mental health and sleep is bidirectional, where sleep problems can exacerbate mental health issues, and vice versa.

Poor Sleep Hygiene:

Unhealthy sleep habits and poor sleep environments, such as irregular sleep schedules, excessive napping, using electronic devices before bedtime, and an uncomfortable sleep environment, can contribute to insomnia.

Medical Conditions:

Certain medical conditions, including chronic pain (such as arthritis), respiratory disorders (like asthma), gastrointestinal issues, neurological conditions, and hormonal imbalances, can disrupt sleep and increase the risk of insomnia.


Some medications, such as certain antidepressants, stimulants, corticosteroids, and medications for high blood pressure, can interfere with sleep and contribute to insomnia as a side effect.


Insomnia becomes more common with age. Older adults may experience changes in sleep patterns, increased medical conditions, or medication use, making them more susceptible to sleep disturbances.


Women are more likely than men to experience insomnia, possibly due to hormonal changes (such as during menstruation, pregnancy, or menopause) that can affect sleep.

Shift Work or Irregular Schedules:

Working night shifts or irregular hours can disrupt the body’s natural sleep-wake cycle (circadian rhythm), leading to difficulties falling asleep or staying asleep.

Genetic Factors:

There might be a genetic predisposition to insomnia, as some individuals may be more susceptible to sleep disturbances due to genetic variations related to sleep regulation.

Substance Use:

Consuming substances such as caffeine, nicotine, and alcohol, especially close to bedtime, can disrupt sleep patterns and contribute to insomnia.

Environmental Factors:

Noisy or brightly lit sleep environments, uncomfortable temperatures, or disturbances from partners’ snoring or other household noises can impact sleep quality and contribute to insomnia.

Identifying and managing these risk factors can be essential in preventing or treating insomnia disorder. Addressing underlying causes, adopting healthy sleep habits, and seeking professional help when necessary can significantly improve sleep quality and reduce the impact of insomnia on daily life.

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Treatment for Insomnia Disorder

Treatment for insomnia disorder typically involves a combination of approaches tailored to the individual’s specific circumstances and the underlying causes of their sleep difficulties. Here are various treatment options commonly used for managing insomnia disorder:

Cognitive-Behavioral Therapy for Insomnia (CBT-I):

CBT-I is a structured, evidence-based therapy that aims to change thoughts, behaviors, and attitudes surrounding sleep. It includes techniques such as stimulus control, sleep restriction, relaxation training, and cognitive restructuring to improve sleep quality.

Sleep Hygiene Practices:

Encouraging healthy sleep habits, such as maintaining a consistent sleep schedule, creating a comfortable sleep environment, avoiding stimulating activities before bedtime, and limiting caffeine and alcohol intake, can significantly improve sleep quality.

Stimulus Control Therapy:

This therapy aims to associate the bed and bedroom environment with sleep by limiting activities done in bed to sleep and intimacy, thereby strengthening the connection between bed and sleep.

Sleep Restriction Therapy:

This technique involves restricting the time spent in bed to match the actual amount of time spent sleeping, aiming to consolidate sleep and improve sleep efficiency.

Relaxation Techniques:

Practices such as progressive muscle relaxation, deep breathing exercises, guided imagery, or mindfulness meditation can help reduce stress, calm the mind, and promote relaxation conducive to sleep.


This technique involves using electronic devices to monitor and provide feedback on physiological measures (such as heart rate or muscle tension) to teach relaxation and stress reduction techniques.


In certain cases, doctors may prescribe medications for short-term relief from insomnia. These medications may include sedative-hypnotics (such as benzodiazepines or non-benzodiazepine hypnotics) or other sleep aids. However, these are typically recommended for short-term use due to the potential for dependency and other side effects.

Light Therapy:

This treatment involves exposure to specific wavelengths of light to regulate circadian rhythms and improve sleep patterns, often used for certain types of circadian rhythm disorders or jet lag.

Addressing Underlying Conditions:

Treating underlying medical conditions, such as pain, respiratory issues, or mental health disorders like anxiety or depression, can help alleviate associated sleep disturbances.

Professional Guidance:

Seeking guidance from healthcare professionals, sleep specialists, or therapists experienced in treating sleep disorders can provide personalized strategies and support tailored to an individual’s needs.

It’s essential to consult with a healthcare provider or sleep specialist to determine the most suitable treatment approach for insomnia disorder. The combination of behavioral strategies, lifestyle modifications, and, if necessary, targeted medications can often be effective in improving sleep quality and managing insomnia.

Therapies for Insomnia Disorder

Several effective therapies are commonly used to address insomnia disorder, focusing on behavioral changes, cognitive restructuring, and relaxation techniques. Here are some prominent therapies used for managing insomnia disorder:

Cognitive-Behavioral Therapy for Insomnia (CBT-I):

CBT-I is considered the gold standard and most extensively studied non-pharmacological treatment for insomnia. It involves various techniques targeting maladaptive thoughts, behaviors, and habits related to sleep. Components of CBT-I include:

Sleep Restriction:

Limiting the time spent in bed to match the actual time spent asleep, gradually increasing sleep efficiency.

Stimulus Control:

Associating the bed and bedroom environment solely with sleep by limiting activities done in bed to sleep and intimacy.

Cognitive Restructuring:

Identifying and challenging negative thoughts and worries about sleep, replacing them with more realistic and positive beliefs.

Sleep Hygiene Education:

Educating individuals about healthy sleep habits and optimizing their sleep environment.

Relaxation Techniques:

Various relaxation methods can help calm the mind and body, making it easier to fall asleep. These techniques include:

Progressive Muscle Relaxation:

Sequential tensing and relaxing of muscle groups to reduce physical tension.

Deep Breathing Exercises:

Controlled breathing patterns to induce relaxation.

Mindfulness Meditation:

Focused attention on the present moment, promoting relaxation and reducing stress.


Biofeedback uses sensors to monitor physiological functions such as muscle tension, heart rate, or skin temperature. Individuals learn to control these functions, aiding relaxation and stress reduction conducive to sleep.

Light Therapy:

Light therapy involves exposure to specific wavelengths of light to regulate circadian rhythms. It’s especially useful for individuals with circadian rhythm disorders or those experiencing jet lag.

Brief Behavioral Treatment for Insomnia (BBTI):

BBTI is a streamlined version of CBT-I that focuses on behavioral strategies like stimulus control, sleep restriction, and sleep hygiene, making it suitable for a wider range of individuals.

Multicomponent Interventions:

Some therapeutic approaches combine different elements of behavioral and cognitive therapies to address various aspects contributing to insomnia disorder.

It’s essential for individuals with insomnia disorder to consult with a healthcare professional, preferably one specializing in sleep medicine or behavioral sleep medicine, to determine the most suitable therapy or combination of therapies tailored to their specific needs. These therapies often involve behavioral changes, cognitive restructuring, and relaxation techniques aimed at improving sleep quality and duration without relying solely on medication.

Preventions of Insomnia Disorder

Preventing insomnia disorder involves adopting healthy sleep habits and managing potential triggers or risk factors that can contribute to sleep disturbances. While it’s not always possible to completely prevent insomnia, certain practices can promote better sleep and reduce the likelihood of developing chronic sleep difficulties. Here are some preventive measures for insomnia disorder:

Maintain a Consistent Sleep Schedule:

Establish a regular sleep routine by going to bed and waking up at the same time every day, even on weekends, to regulate your body’s internal clock.

Create a Relaxing Bedtime Routine:

Develop calming bedtime rituals to signal to your body that it’s time to wind down. This might include reading, taking a warm bath, practicing relaxation techniques, or listening to soothing music.

Optimize Your Sleep Environment:

Ensure your bedroom is conducive to sleep by making it comfortable, quiet, cool, and dark. Consider using blackout curtains, white noise machines, or earplugs if needed.

Limit Stimulants and Substances:

Reduce or avoid consuming caffeine, nicotine, and alcohol, especially close to bedtime, as they can interfere with sleep quality and disrupt your ability to fall asleep.

Limit Screen Time Before Bed:

Avoid using electronic devices (such as phones, tablets, computers, or TVs) at least an hour before bedtime, as the blue light emitted by screens can interfere with the production of the sleep hormone melatonin.

Manage Stress:

Practice stress-reduction techniques such as mindfulness, meditation, yoga, or deep breathing exercises to alleviate stress and promote relaxation before bedtime.

Exercise Regularly:

Engage in regular physical activity, but avoid vigorous exercise close to bedtime. Regular exercise can promote better sleep, but intense workouts right before bed might be too stimulating.

Watch Your Diet:

Be mindful of your eating habits, especially in the evening. Avoid heavy meals, large amounts of liquids, and spicy or acidic foods close to bedtime to prevent discomfort that may disrupt sleep.

Establish a Winding Down Period:

Allocate some time to wind down and relax before bedtime. Engage in calming activities that help transition your mind and body from wakefulness to sleep.

Seek Help for Persistent Sleep Problems:

If occasional sleep difficulties persist or become chronic, seek guidance from a healthcare professional or sleep specialist. Early intervention can prevent acute sleep problems from developing into chronic insomnia.

By adopting healthy sleep habits, managing stress, and creating a conducive sleep environment, individuals can reduce the risk of developing insomnia disorder and improve overall sleep quality. Consistency in these practices is key to maintaining healthy sleep patterns over time.

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