Insomnia — Causes, Types, and Evidence-Based Treatments (2026)
- CBT-I (Cognitive Behavioural Therapy for Insomnia) is more effective than sleeping pills long-term
- Chronic insomnia affects 1 in 3 adults in the UK and USA
- Sleep restriction therapy — the counterintuitive CBT-I technique — is the most powerful single insomnia intervention
- Sleeping pills provide short-term relief but cause rebound insomnia when stopped
- The most common cause of insomnia is conditioned arousal — the brain associating the bed with wakefulness
What Is Insomnia?
Insomnia is defined as persistent difficulty falling asleep, staying asleep, or experiencing restorative sleep — occurring at least 3 nights per week for 3 months or more — despite adequate opportunity and circumstances to sleep, causing daytime impairment. Insomnia affects approximately 30–35% of adults, with 10% meeting criteria for chronic insomnia disorder.
Types of Insomnia
- Sleep onset insomnia: Difficulty falling asleep at the start of the night — most commonly caused by anxiety and cognitive arousal
- Sleep maintenance insomnia: Waking frequently during the night or waking too early — more common in depression, sleep apnoea, and older adults
- Early morning awakening: Waking 2–3 hours before desired time and unable to return to sleep — strongly associated with depression
Root Causes of Chronic Insomnia
The 3-P model explains why insomnia becomes chronic:
- Predisposing factors: Genetic vulnerability, anxious personality, high physiological arousal
- Precipitating factors: Stressful life event, illness, medication that first triggered sleeplessness
- Perpetuating factors: The behaviours and thoughts that maintain insomnia — spending too long in bed, daytime napping, clockwatching, catastrophising about sleep loss
The most important perpetuating factor is conditioned arousal: after nights of lying awake, the brain learns to associate the bed with wakefulness and anxiety rather than sleep. This is why CBT-I — which directly addresses perpetuating factors — works so effectively.
CBT-I — The Gold Standard Treatment
Sleep Restriction Therapy
The most powerful CBT-I component. Involves temporarily restricting time in bed to match actual sleep time (e.g., if sleeping 5 hours in an 8-hour window, restrict to 5 hours in bed). This builds sleep drive, reduces conditioned arousal, and — paradoxically — produces deeper, more consolidated sleep. Most people see improvement within 2 weeks despite initial sleep deprivation.
Stimulus Control
- Use the bed only for sleep and sex — no phone, TV, or reading in bed
- Get out of bed if awake for more than 20 minutes — go to another room until sleepy
- Wake at the same time every day regardless of how much you slept — even weekends
- Do not nap during the day
Cognitive Restructuring
Challenging catastrophic thoughts about sleep ('I cannot function without 8 hours' / 'I will be ill if I do not sleep') that create the anxiety perpetuating insomnia. These thoughts are understandable but factually inaccurate — one night of poor sleep does not cause the harm patients fear.