Pathogenesis, Risk Factors & Development
Pathogenesis of insomnia disorder is not understood and there have been a number of models to explain including psychological-behavioral models such as the 3P model proposed by Spielman et al.Spielman AJ, et al. A behavioral perspective on insomnia treatment. Psychiatric Clinics of North America 1987;10:541–553 and neurobiological models such as the insomnia model of Buysse et al.Buysse DJ, et al. A Neurobiological Model of Insomnia. Drug Discov Today Dis Models 2011;8(4):129–137 The latter. hypothesizes based on basic and clinical neuroscience findings that insomnia results from persistent activity in wake- promoting neural structures during NREM sleep.
Source: Alexander Sweetman
Predisposing factors place an individual at greater risk of developing insomnia:
- Increased anxiety, stress or worry
- Inappropriate expectations about sleep (e.g. to obtain more sleep than is necessary, or to obtain an unbroken sleep throughout the night)
- Genetically determined factors (e.g. increased core body temperature during the sleep period, increased stress-reactivity)
Precipitating factors initiate the insomnia:
- Stressful life event (e.g. death in family, relationship difficulties, job loss, starting a new job, newborn)
- Pain
- Menopause
- Shift work (day and night shifts) including hospitality work
- Travel between time zones
- Circadian disruption (e.g. daylight savings)
- Environmental factors (e.g. noise disturbance, temperature)
- Lifestyle risk factors including the use of non-illicit substances that contain caffeine (e.g. coffee and black tea, energy drinks, gels, shots, electrolyte replacements, protein, meal/weight replacement shakes) and alcohol
- Medication:
i. Medication with stimulant properties effects through the central nervous system (e.g. pseudoephedrine, phenytoin) ii. Adrenergic agonists (e.g. salbutamol, dexamphetamine, methylphenidate or modafinil) iii. Glucocorticoids iv. Antidepressants (selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs)) v. Nocturia (e.g. diuretics) vi. Respiratory suppression medication (e.g. opioids) vii. Corticosteroids viii. Anti-Parkinson drugs (e.g. levodopa) ix. Beta blockers (causing bad dreams) x. Statins xi. Stimulant laxatives xii. Appetite suppressants xiii. Chronic benzodiazepine use |
- Medical disorders:
i. Respiratory (e.g. shortness of breath, asthma, chronic obstructive airway disease) ii. Cardiovascular (e.g. congestive heart failure, ischaemic heart disease) iii. Endocrine (e.g. thyroid abnormalities, diabetes, menopause) iv. Neurological (e.g. neurodegenerative conditions such as Alzheimer’s disease or Parkinson’s disease, neuromuscular disorders, traumatic brain injury, stroke, chronic pain, chronic fatigue syndrome, concussion) v. Gastro-oesophageal reflux vi. Frequent nocturia vii. Itch (e.g. eczema) |
- Mental health (psychiatric) disorders (which often have a bidirectional relationship with insomnia)
- Other sleep health disorders (e.g. obstructive sleep apnea, restless legs syndrome)
Perpetuating factors self-maintain the insomnia disorder, and are a common target of non-pharmacological therapies such as Brief Behavioural Therapy for insomnia (BBTi) and Cognitive Behavioural Therapy for insomnia (CBTi):
- Conditioned insomnia or learned insomnia
- Heightened anxiety (e.g. anxiety about poor sleep may overtake anxiety concerning the work or personal events that may have been prominent at the time the insomnia symptoms had their onset)
- Inappropriate behaviours and use of sleep aids (e.g. excessive alcohol, watching TV in bed, mobile phone use in bed)
- Repeated association of the bed environment with unsuccessful attempts to initiate sleep or return to sleep after awakening, wakefulness and frustration
- Counter-productive compensatory behaviours (e.g. spending too much time in bed at night and/or napping during the day to make up for the lack of sleep, cancelling daytime commitments including lack of physical activity or exercising late in the day)
- Misperceptions about the quality and quantity of sleep (e.g. underestimating the amount of time spent asleep, leading to increased sleep-related anxiety)
- Dysfunctional beliefs about sleep (e.g. misconception that a few brief night-time awakenings are abnormal)
AHI - Apnoea-Hypopnoea Index
BBTi - Brief Behavioural Therapy for Insomnia
BMI - Body Mass Index (kg/m2)
BQ - Berlin Questionnaire
CBTi - Cognitive Behavioural Therapy for Insomnia
CELL - Coblation Endoscopic Lingual Lightening
COPD - Chronic Obstructive Pulmonary Disease
CVA - Cerebrovascular Accident
CPAP - Continuous Positive Airway Pressure
CSA - Central Sleep Apnoea
DASS - Depression Anxiety Stress Scale
DBAS - Dysfunctional Beliefs and Attitudes about Sleep
DBP - Diastolic Blood Pressure
DIMS - Difficulties Initiating and/or Maintaining Sleep
DISE - Drug-Induced Sleep Endoscopy
DISS - Daytime Insomnia Symptom Scale
ENT - Ear Nose and Throat
ESS - Epworth Sleepiness Scale
FOSQ - Functional Outcomes of Sleep Questionnaire
FSH - Follicle-Stimulating Hormone
FTP - Friedman Tong Position
GP - General Practitioner
HANDI - RACGP Handbook of Non-Drug Interventions
HGNS - Hypoglossal Herve Htimulation
ISI - Insomnia Severity Index
K10 - Kessler Psychological Distress Scale
MAD - Mandibular Advancement Device
MAS - Mandibular Advancement Rplint
MBS - Medicare Benefits Schedule
MMA - Maxillomandibular Advancement Surgery
MRA - Mandibular Repositioning Appliance
ODI - Oxygenation Desaturation Index
OSA - Obstructive Sleep Apnoea
PLMD - Periodic Limb Movement Disorder
PT - Positional Therapy
PTSD - Post-Traumatic Stress Disorder
PSG - Polysomnography
QSQ - Quebec Sleep Questionnaire
REM - Rapid Eye Movement
RFTB - Radiofrequency Thermotherapy of the Tongue Base
SBP - Systolic Blood Pressure
SCI - Sleep Condition Indicator
SE - Sleep Efficiency
SF36 - Short-Form (36) Health Survey
SMILE - Submucosal Minimally Invasive Lingual Excision
SNRIs - Serotonin-Norepinephrine Reuptake Inhibitors
SOL - Sleep Onset Latency
SSRI - Selective Serotonin Reuptake Inhibitors
TFTs - Thyroid Function Tests
TIB - Time In Bed
TORS - Transoral Robotic Surgery
TST - Total Sleep Time
UPPP - Uvulopalatopharyngoplasty
WASO - Wake After Sleep Onset