Insomnia is the most prevalent sleep disorder, affecting approximately 10–15% of adults chronically and up to 35% experiencing significant symptoms at any given time. Despite its prevalence, it remains poorly understood by most sufferers — who often treat it with willpower, supplements, or medication rather than the evidence-based behavioural approaches that produce the most durable results. This guide explains what actually causes insomnia to persist and what works to resolve it.
Understanding Why Insomnia Persists: The 3P Model
The most clinically useful framework for understanding chronic insomnia is the 3P model developed by Dr. Arthur Spielman:
- Predisposing factors: Biological vulnerability to hyperarousal — some people's nervous systems are more easily activated and harder to quiet. This is partly genetic and explains why some people develop insomnia after stress while others with the same stressors sleep fine.
- Precipitating factors: The trigger that first disrupts sleep — a stressful life event, illness, job change, relationship breakdown, bereavement, shift work change, or medication side effect. Nearly everyone has occasional insomnia triggered by life events.
- Perpetuating factors: The behaviours and beliefs that maintain insomnia after the original precipitant has resolved. This is where chronic insomnia lives. Examples: spending excessive time in bed trying to "catch up," napping, abandoning routines, developing sleep performance anxiety, checking the clock, catastrophising about sleep loss.
This model is important because it explains why treating the precipitant (the original stressor) often doesn't resolve chronic insomnia — by the time the stress resolves, the perpetuating factors have taken over as the primary driver.
Common Causes of Insomnia
Psychological Causes
- Anxiety: Hyperarousal from anxiety is both a cause and consequence of insomnia. Anxious rumination at bedtime, physiological tension, and a hypervigilant nervous system all impede sleep onset and maintenance.
- Depression: Insomnia — particularly early morning waking — is both a symptom and risk factor for depression. The two conditions are bidirectionally linked.
- PTSD: Hyperarousal, nightmares, and conditioned fear responses around sleep are central features of PTSD-related insomnia.
- Performance anxiety about sleep: Ironically, trying too hard to sleep is itself a cause of insomnia. The arousal generated by monitoring sleep attempts, watching the clock, and catastrophising about the consequences of not sleeping maintains the insomnia independently of the original cause.
Behavioural Causes
- Inconsistent sleep schedule: Variable bedtimes and wake times disrupt circadian rhythms, making reliable sleep onset difficult.
- Excessive time in bed: Spending 9–10 hours in bed while only sleeping 6 hours dilutes sleep pressure and fragments the sleep that does occur.
- Screen use in bed: Maintains arousal, suppresses melatonin, and associates bed with wakefulness.
- Late caffeine and alcohol: Both disrupt sleep architecture — caffeine by blocking adenosine, alcohol by suppressing REM and slow-wave sleep.
Medical Causes
- Chronic pain, including back pain, arthritis, fibromyalgia
- Restless legs syndrome
- Hyperthyroidism
- Acid reflux (GERD) — often worse when lying flat
- Nocturia (frequent nighttime urination, sometimes due to undiagnosed sleep apnea)
- Medication side effects (stimulants, certain antidepressants, corticosteroids, beta-blockers)
Evidence-Based Remedies for Insomnia
Cognitive Behavioural Therapy for Insomnia (CBT-I) — First-Line Treatment
CBT-I is the gold-standard treatment for chronic insomnia, recommended as first-line by the American College of Physicians, NICE (UK), and the American Academy of Sleep Medicine — over medication. Meta-analyses consistently show CBT-I produces larger effect sizes than sleep medication and, unlike medication, produces improvements that persist after treatment ends. CBT-I typically involves 6–8 sessions with a trained therapist and addresses:
- Sleep restriction therapy: Temporarily limiting time in bed to match actual sleep time, then gradually extending as sleep efficiency improves. This builds powerful sleep pressure that reliably produces deeper, consolidated sleep. Counterintuitive but highly effective — the most active component of CBT-I.
- Stimulus control: Rebuilding the association between bed and sleepiness by restricting bed use to sleep and sex, and leaving bed when unable to sleep.
- Cognitive restructuring: Identifying and challenging unhelpful beliefs about sleep ("I must get 8 hours or I can't function," "I'll never sleep normally").
- Sleep hygiene education: Addressing lifestyle factors that perpetuate insomnia.
- Relaxation techniques: PMR, breathing exercises, and mindfulness to reduce physiological arousal.
CBT-I is available through licensed therapists, online programs (Sleepio, Insomnia Coach), and in-person sleep clinics. Our free Insomnia Relief Plan tool provides a personalised 4-week CBT-I based plan as a starting point.
Sleep Restriction Therapy (As a Standalone)
The most powerful single component of CBT-I. The basic protocol: calculate your average actual sleep time (e.g., 5.5 hours). Set your time in bed to match this plus 30 minutes (e.g., 11pm to 6:30am). Maintain a rigid wake time. As sleep efficiency (time asleep ÷ time in bed) exceeds 85%, extend the window by 15 minutes. This process typically takes 4–8 weeks and produces significant, lasting improvements. It feels brutal initially — it is intentionally sleep-depriving in the short term to drive consolidation.
Melatonin (Limited Role)
Melatonin is not a sleep drug — it is a circadian signal. It is most useful for shifting the timing of sleep (circadian rhythm disorders) rather than treating hyperarousal-driven insomnia. For insomnia, doses of 0.5–1mg taken 1–2 hours before intended sleep may reduce sleep onset slightly. Higher doses (the 5–10mg products widely sold in the US) are not more effective and may impair the body's own melatonin production over time. For a detailed discussion, see our article on the role of melatonin in sleep regulation.
Prescription Sleep Medication (Last Resort)
Prescription sleep medications — including benzodiazepines and Z-drugs (zolpidem/Ambien, eszopiclone/Lunesta) — are indicated for short-term management of acute insomnia (under 4 weeks) and not for chronic insomnia. They produce dependency, rebound insomnia on discontinuation, suppress slow-wave sleep despite increasing total sleep time, and have significant cognitive and motor side effects (particularly in older adults). They should be used only under medical supervision and as a bridge, not a solution.
Medical disclaimer: This article is for informational purposes only. Chronic insomnia is a medical condition — if your sleep problems are significantly impairing your functioning, please consult a qualified healthcare provider or sleep specialist.
About the author: Morgan Wells is a certified sleep analyst and wellness writer with over a decade of experience in behavioral sleep health. Learn more about Morgan.