Insomnia

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Overview
Historical Perspective
Classification
Pathophysiology
Causes
Differentiating Insomnia from other Diseases
Epidemiology and Demographics
Risk Factors
Screening
Natural History, Complications and Prognosis
Diagnosis
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History and Symptoms
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Cost-Effectiveness of Therapy
Future or Investigational Therapies
Case Studies
Case #1
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Amber Ehsan Faquih, MD[2] Kiran Singh, M.D. [3], Jyostna Chouturi, M.B.B.S [4]

Synonyms and keywords: Insomnia disorder

Historical Perspective

A team headed by Professor Özçelik first dicovered the insomnia gene in 2017, after almost eight years of research. They proved that the mutations in Cryptochrome 1 (CRY1), one of the genes controlling the biological clock, could cause deteriorations in sleep cycle and circadian rhythm.

Pathophysiology

It is thought that insomnia is mediated by:

• Molecular Mechanism
  • Hormones causing wakefulness: Catecholamine, Histamine, Orexin
  • Hormones promoting sleep: Adenosine, serotonin, GABA, melatonin, Prostaglandin D2
• Hyperarousal model
  • Cognitive
  • Physiologic
  • Cortical
• Genetic: ApoE4, PER3, 5HTTLPR, Single Nucleotide Polymorphism, CLOCK gene, HLA DQI*002
• Sleep switch Model (Orexin mediated)
  • Sleep promoting areas:Ventrolateral Preoptic and Median preoptic Nucleus
  • Wake promoting areas: Tuberomammillary nucleus, dorsal raphe, Locus coeruleus
• Cognitive and Behavioural Model(3P model): This model of insomnia helps to explain how acute insomnia becomes chronic and aids in assessing insomnia in individual patients
  • Precipitating factors
  • Predisposing factors
  • Perpetuating factors

Classification

Insomnia has been classified by the International Classification of Sleep Disorders, 2nd Edition into 11 categories:

• Psychophysiologic insomnia (primary insomnia)
• Adjustment insomnia (acute insomnia)
• Paradoxical insomnia
• Behavioral insomnia of childhood
• Primary sleep disorders causing insomnia
• Idiopathic insomnia
• Inadequate sleep hygiene
• Insomnia due to mental disorder
• Insomnia due to drug or substance abuse
• Insomnia due to a medical condition
• Insomnia not due to a substance or known physiologic condition, unspecified

Insomnia has also been classified by the International Classification of Sleep Disorder, 3rd Edition into:

• Chronic Insomnia Disorder
• Short-term Insomnia Disorder
• Other Insomnia Disorder

Causes

Symptoms may include waking up a night, waking up too early, difficulty falling asleep at night, daytime fatigue, impaired concentration and recall, irritability, Constant worries about sleep, Depression, anxiety and increased accidents or error prone.

Common causes include:

• Excess consumption of caffeine, nicotine and alcohol
• Medication induced
  • Prescription drugs
  • Over the counter drugs
• Bad sleep habits: Using bed for work, eating or any other leisure, disrupted bedtime schedule, frequent naps, stimulating activities before bed, disturbed sleep environment.Use of electronic gadgets just before bed can also interfere with the sleep cycle.
• Eating too much before bedtime causing GI discomfort or heartburn while lying down.
• Jet lags, Constant change in shifts, working too late or an early shift can disrupt the body's circadian rhythm
• Trauma and Stressful life experiences
• Depression or Anxiety or PTSD
• Medical conditions like GERD, chronic pain, cancer, cardiac diseases, asthma, overactive thyroid, urinary complaints in elderly.
• Sleep-related disorders like Restless leg syndrome and sleep apnea

Epidemiology and Demographics

Gender

Females have a higher prevalence of insomnia in adolescence and especially high during menopause.

Age

Higher prevalence of insomnia in the elderly population.

Socioeconomic status

More common in those with poor health, low socioeconomic status and quality of life.

Risk Factors

Common risk factors for insomnia include:

• Gender(Female)
• Increasing age
• Depression
• Unemployed
• Widow/Divorced/Separated
• Lower educational qualification
• Economic inactivity
• Military Deployment
• Racial Discrimintion

Diagnosis

History and Symptoms | Physical Examination | Laboratory Findings | Other Diagnostic Studies

DSM-5 diagnostic criteria for insomnia includes:

• Symptoms occur ≥ 3 days/week for ≥ 3 months
• Symptoms cause functional impairment or distress
• Problems initiating or maintaining sleep, or awakening early in the morning and being unable to return to sleep
• Symptoms occur despite having enough time to sleep
• Symptoms are not caused by an underlying substance or medication use
• No underlying or coexisting psychiatric or medical disorder that explains symptoms

The doctor won’t be able to confirm an insomnia diagnosis in some cases without further testing. Following are the tests one might have to undergo.

• Sleep study: Overnight sleep stud or the polysomnogram test.In this study, one has to spend the night at a sleep center with sensors on the face, scalp, eyelids, one finger, chest and limbs. The sensors then monitor brain wave activity, oxygen level, heart rate, respiratory rate and muscle movement that occur prior, during, and post sleep. Also, some daytime tests monitor sleep latency during a series of naps, evaluate abilities to stay awake and alert after a night of normal sleep. However, irrespective of home-based monitoring kits or the procedures mentioned above, they will be non-invasive and pain-free.
• Actigraphy: Actigraphy tests, similar to overnight sleep studies, but most are conducted at home. In this one has to wear a sensor on the wrist or ankle to monitor their sleep and wakefulness pattern. Recommended Duration for wearing the sensors is three to 14 consecutive days. Actigraphy is safe for children and adults, though the sensor may cause some light – albeit temporary – irritation.
• Blood tests: Medical conditions can also cause/exacerbate sleep. Based on the questionnaire and physical exam, the doctor may recommend blood tests to check for other pre-existing conditions.

If the diagnostic criteria for chronic or short-term insomnia based on the sleep disorder test are met, then we may advance to insomnia treatment.

Treatment

Medical Therapy | Non-pharmacological therapy | Primary Prevention | Secondary Prevention | Cost-Effectiveness of Therapy | Future or Investigational Therapies

Management is guided by available clinical practice guidelines.

Case Studies

Case #1

See also

• Chronic colestites/total insomnia

• Fatal familial insomnia
• Sleep deprivation
• Delayed sleep phase disorder
• Actigraphy

References

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