Insomnia — Causes, Symptoms & Treatment Guide — Symptoms, Causes & Treatment | MyMedicPlus

Insomnia is a sleep disorder characterised by persistent difficulty initiating sleep (sleep-onset insomnia), maintaining sleep (sleep-maintenance insomnia — frequent nocturnal awakenings, early morning awakening), or experiencing non-restorative sleep, despite adequate opportunity and circumstances for sleep, resulting in significant daytime functional impairment. Insomnia disorder (chronic insomnia) is defined by these symptoms occurring at least 3 nights per week for at least 3 months. Insomnia is the most common sleep complaint globally — affecting 30-45% of adults with some insomnia symptoms and 10-15% meeting criteria for chronic insomnia disorder. It has profound impacts on physical health (increased risk of depression, anxiety, cardiovascular disease, type 2 diabetes, immune dysfunction, and all-cause mortality), cognitive function (impaired memory, concentration, and reaction time), occupational performance, and quality of life.

The 3P model (Spielman) describes insomnia through: Predisposing factors (biological vulnerability — hyperarousal tendency, genetic predisposition, female sex, older age, neuroticism, anxiety temperament); Precipitating factors (acute triggers — stressful life events, bereavement, job loss, illness, shift work, jet lag, change in sleep environment); Perpetuating factors (maladaptive behaviours that maintain insomnia beyond the initial trigger — excessive time in bed, irregular sleep schedules, daytime napping, anxiety about sleep, catastrophising insomnia consequences, conditioned arousal to the bed). Common comorbidities that cause or worsen insomnia: depression (insomnia is both a symptom and a risk factor for depression), anxiety disorders (GAD, PTSD), chronic pain conditions, respiratory disorders (COPD, obstructive sleep apnoea), restless legs syndrome, gastro-oesophageal reflux, menopause (hot flushes), shift work disorder, and stimulant medications (steroids, bronchodilators, some antidepressants). Substances: alcohol (initially sedating but disrupts REM sleep and causes early morning awakening), caffeine (half-life 5-6 hours — afternoon consumption impairs sleep onset), and nicotine.

Night-time symptoms: difficulty falling asleep (lying awake for 30+ minutes), difficulty staying asleep (frequent awakenings with difficulty returning to sleep), waking 30-60 minutes before the desired time and being unable to return to sleep (early morning awakening — classic in depression), and subjective sense of non-refreshing or unrestorative sleep. Daytime consequences (required for diagnosis): fatigue and low energy, difficulty concentrating or poor memory (cognitive impairment), mood disturbance (irritability, anxiety, low mood), reduced motivation, performance errors, accidents, social or occupational impairment, and daytime sleepiness (less prominent than in sleep apnoea — insomniacs are typically hyperaroused and unable to nap despite fatigue). The hyperarousal state: insomnia is characterised by physiological, cognitive, and emotional hyperarousal — elevated cortisol, increased heart rate variability, heightened brain activity at night, intrusive thoughts, monitoring clock or sleep cues, and heightened attention to potential sleep threats. Sleep anxiety ('somniphobia') — fear of the bedroom and bedtime — perpetuates insomnia.

Insomnia is a clinical diagnosis based on detailed sleep history — the ICSD-3 (International Classification of Sleep Disorders) or DSM-5 criteria are used. Key elements: sleep onset latency, number and duration of nocturnal awakenings, wake after sleep onset, early morning awakening time, total sleep time, time in bed, sleep quality, sleep variability, history and duration, and daytime impairment. Sleep diary: 2-week prospective sleep diary (recording bedtime, sleep onset, awakenings, wake time, total sleep time) is essential for objective characterisation and guides treatment. Epworth Sleepiness Scale (ESS): quantifies daytime sleepiness — high scores suggest obstructive sleep apnoea (OSA) rather than insomnia (OSA patients are typically sleepier). ISI (Insomnia Severity Index): validated questionnaire scoring insomnia severity (0-28 scale). Actigraphy (wrist movement sensor worn for 2 weeks): objective activity-rest patterns corroborate diary data. Polysomnography (PSG — overnight sleep study): not routinely required for uncomplicated insomnia; indicated if OSA, periodic limb movement disorder, or parasomnia suspected. Blood tests: FBC, TFTs (hypothyroidism causes fatigue/sleepiness), ferritin (restless legs), HbA1c, cortisol. Screen for depression, anxiety, PTSD with validated tools (PHQ-9, GAD-7, PCL-5).

Cognitive-Behavioural Therapy for Insomnia (CBT-I) is the first-line and most effective treatment — recommended in preference to medication by NICE, AASM, and ESS guidelines. CBT-I is a 6-8 session structured programme combining: Stimulus control therapy (reassociating the bed with sleep — get out of bed if unable to sleep within 20 minutes; use the bed only for sleep and sex; no TV, phone, or reading in bed; establish a fixed wake time); Sleep restriction therapy (temporarily restricting time in bed to actual sleep time — initially typically 5-6 hours — then gradually extending; the mild sleep deprivation consolidates sleep and strengthens homeostatic drive); Sleep hygiene education (sleep environment optimisation — dark, cool, quiet; regular sleep and wake times; caffeine cut-off time); Cognitive therapy (challenging dysfunctional beliefs and catastrophic thoughts about sleep; reducing sleep monitoring; mindfulness); and Relaxation training (progressive muscle relaxation, abdominal breathing, imagery). Digital CBT-I (Sleepio, Somryst app) is effective and scalable — recommended when face-to-face CBT-I is unavailable. Pharmacotherapy (short-term only — 2-4 weeks maximum): Non-benzodiazepine z-drugs — zopiclone (7.5mg) and zolpidem (10mg): GABA-A agonists; rapid onset; improve sleep onset and maintenance; risk of dependence, rebound insomnia, and next-day impairment; not recommended in elderly (falls risk). Melatonin prolonged-release (Circadin 2mg): licensed for insomnia in patients over 55 only; low side-effect profile; resynchronises circadian rhythm; modest efficacy. Daridorexant (Quviviq — orexin receptor antagonist): newest licensed insomnia treatment; reduces wakefulness drive; no dependence liability; licensed for adults. Low-dose doxepin (3-6mg) — antihistamine action; improves sleep maintenance in older adults.

Chronic insomnia is a significant independent risk factor for multiple serious health outcomes. Cardiovascular disease: meta-analyses show a 45% increased risk of hypertension, 20–30% increased risk of myocardial infarction, and approximately 15% increased stroke risk in individuals with chronic insomnia combined with objectively short sleep duration (less than 6 hours). Type 2 diabetes risk is elevated approximately 40–55% in people with persistent poor sleep — insulin sensitivity is impaired after even one night of sleep restriction. Depression: insomnia is the single most powerful modifiable risk factor for incident depression — people with persistent insomnia have a 2–3x higher risk of developing major depressive disorder. Cognitive impairment from chronic sleep loss affects memory consolidation, sustained attention, working memory, and decision-making. All-cause mortality is elevated with persistent short sleep duration. Occupational impairment (absenteeism, presenteeism, errors) and road traffic accident risk from fatigue are significant burden outcomes. Relationship strain and reduced quality of life are frequently reported. Dependency risk from inappropriate prolonged use of z-drugs or benzodiazepines is an important iatrogenic complication.

Sleep hygiene practices should be universal. Maintain a consistent sleep-wake schedule (including weekends) — anchor sleep to a fixed wake time. Create a sleep-conducive environment: cool (16-18°C), dark (blackout blinds), quiet, and comfortable. Avoid caffeine after 2pm (half-life 5-6 hours means afternoon coffee significantly raises bedtime caffeine levels). Avoid alcohol as a sleep aid — disrupts sleep architecture and causes early morning awakening. Limit screen time (blue light suppresses melatonin) in the hour before bed — use blue-light blocking glasses or night mode. Regular moderate aerobic exercise (150 minutes/week) significantly improves sleep quality — avoid vigorous exercise within 2 hours of bedtime. Wind-down routine: 30-60 minutes of relaxing activities before bed (bath, reading, gentle stretching). Bright light therapy in the morning (30 minutes of bright outdoor light or 10,000 lux lightbox) anchors the circadian rhythm. Avoid clock-watching and excessive monitoring of sleep. Treat comorbid mental health conditions (depression, anxiety) — the most important intervention for secondary insomnia.

See your GP for insomnia that has persisted for 3 or more months despite sleep hygiene improvements, is causing significant daytime impairment (affecting work, relationships, or safety), is associated with symptoms of depression or anxiety, or if you are using alcohol or over-the-counter sleep aids regularly. Seek specialist sleep medicine assessment for: snoring with witnessed apnoeas or excessive daytime sleepiness (possible obstructive sleep apnoea), uncomfortable leg sensations (restless legs syndrome), abnormal behaviours during sleep (parasomnias), or insomnia not responding to CBT-I after a full course. Do not attempt to manage severe insomnia with alcohol — this causes dependence and worsens long-term sleep. Digital CBT-I programmes (Sleepio, Somryst) offer effective self-directed treatment options while awaiting specialist input.