Overview
Insomnia is difficulty falling asleep, staying asleep, or waking too early, resulting in daytime impairment. It is classified as acute (less than 3 months) or chronic (3 months or more, at least 3 nights per week). Chronic insomnia affects thinking, mood, performance, and physical health. It is highly treatable, particularly with cognitive behavioural therapy.
How common is it?
About 30 to 35% of adults report some insomnia symptoms. Chronic insomnia disorder affects 6 to 10% of the population. It becomes more common with age and is roughly twice as prevalent in women as in men.
Causes and risk factors
Insomnia results from hyperarousal of the central nervous system, often initially triggered by stress and then maintained by maladaptive sleep habits and beliefs.
Common risk factors
- Psychological: anxiety, depression, stress, worry about sleep itself
- Medical: pain, GERD, asthma, heart failure, restless legs syndrome
- Sleep environment: noise, light, irregular sleep schedule
- Substances: caffeine, alcohol, nicotine, stimulant medications
- Shift work and jet lag disrupting circadian rhythm
- Medications: corticosteroids, SSRIs, some beta-blockers
- Menopause (hot flushes)
- Primary insomnia disorder with no identifiable cause
Symptoms
- Difficulty falling asleep (sleep onset latency over 30 minutes)
- Waking during the night and struggling to return to sleep
- Early morning wakening before desired time
- Non-restorative sleep
- Daytime fatigue, irritability, or mood disturbance
- Difficulty concentrating and poor memory
- Increased errors or accidents
- Preoccupation and anxiety about sleep
When to see a doctor
See a doctor if insomnia has persisted for more than 3 months, significantly affects daytime function, or may be related to an underlying medical or psychiatric condition. Always seek assessment if sleep apnoea is suspected.
Diagnosis
Primarily clinical, using sleep diary over 2 weeks. Pittsburgh Sleep Quality Index and Insomnia Severity Index are validated questionnaires. Polysomnography only if sleep-disordered breathing or parasomnias are suspected.
Treatments
Cognitive behavioural therapy for insomnia (CBT-I)
CBT-I is the recommended first-line treatment. It combines sleep restriction therapy, stimulus control, sleep hygiene education, and cognitive restructuring of unhelpful beliefs about sleep. More effective than sleeping tablets in the long term.
Sleep restriction therapy
Temporarily restricting time in bed to match actual sleep time consolidates sleep, building sleep pressure. Counterintuitive but highly effective when properly supervised.
Short-term pharmacological treatment
Z-drugs (zopiclone, zolpidem) or low-dose sedating antihistamines for short-term use only (2 to 4 weeks maximum). Risk of dependence and rebound insomnia limits long-term use.
Low-dose doxepin or melatonin
Low-dose doxepin (3 to 6mg) approved for insomnia in older adults. Prolonged-release melatonin is licensed for short-term use in over-55s and for sleep-phase problems.
Self-care and lifestyle
- Maintain consistent wake time every day, including weekends
- Avoid caffeine after noon and alcohol within 3 hours of bedtime
- Reserve the bed for sleep and sex only (not phones, laptops, or TV)
- Keep the bedroom cool, dark, and quiet
- Avoid naps during the day if struggling to sleep at night
Prevention
Good sleep hygiene from the start, managing stress actively, and avoiding caffeine and screen overuse in the hours before bed reduce the risk of chronic insomnia developing.