What causes insomnia?
The 3P model in plain English
The 3P model says insomnia tends to grow from three sets of ingredients: Predisposing, Precipitating, and Perpetuating factors.
You can think of them as: what loaded the dice, what flipped the switch, and what keeps the switch jammed on.
- Predisposing factors are things that make you more prone to insomnia, but don’t cause it on their own. Think : being anxious or perfectionistic.
- Precipitating factors are the triggers that start a run of bad nights – think stress, illness, pain, big life events.1
- Perpetuating factors are the habits, thoughts, and reactions that keep insomnia going long after the original trigger has calmed down.12
In a large study following people with acute insomnia over time, differences in these factors helped predict who recovered naturally and who went on to develop persistent insomnia.1
That’s the hopeful bit: if certain factors keep insomnia going, there are also specific things we can do to help ‘undo’ that process.
Predisposing factors: vulnerability to chronic insomnia
Predisposing factors are the background settings that made you more likely to tip into insomnia when life got rough.
They can include:
- Personality traits like higher perfectionism, lower openness to new experiences or higher conscientiousness.1
- A tendency toward higher arousal and insomnia vulnerability – people who are more “wired” by nature can find it harder to bounce back after acute insomnia.1
- A previous episode of insomnia – past insomnia made future insomnia more likely.1
None of these means you’re broken. They just mean your sleep system is a bit more sensitive, so it’s easier for a rough patch to tip into something more lasting.
Precipitating factors: the thing that kicked it off
Precipitating factors are the events or changes that actually start the run of bad nights.
Examples include:
- Stressful life events – work pressure, relationship difficulties, caring responsibilities, financial stress.
- Health events – pain flares, illness, surgery, hormonal changes.
- Other changes that crank up stress or excitement or curiosity – or things that disturb our daily life routines (for example, big transitions, moves, or major worries).
In that same study I mentioned before, people with acute insomnia reported higher recent stress, anxiety, and depression than good sleepers.¹
For some, sleep settled as the stress eased; for others, especially those with more ‘predisposing factors’ the insomnia carried on.
Perpetuating factors: how insomnia becomes “sticky”
Perpetuating factors are the habits and reactions to sleeplessness that inadvertently keep insomnia going. They usually start as reasonable coping strategies and then slowly become part of the problem.
The research highlights patterns like:23
- Extending time in bed
- Going to bed earlier “just in case” or sleeping in to “try to catch up”.
- Spending more time in bed awake, thinking and worrying.
- Napping and dozing
- Daytime naps (on the sofa, on the train, at weekends) that reduce sleep pressure, making it harder to sleep deeply at night.
- Inconsistent schedules
- Variable bedtimes and wake‑times, especially at weekends, which make it harder for your body clock to find a rhythm.
- Sleep‑related preoccupation and worry
- Getting very focused on sleep, checking constantly how you’re feeling, Googling endlessly, or structuring your whole life around protecting sleep.1
Cognitive‑behavioural treatments for insomnia deliberately target these perpetuating factors: things like time in bed, regular wake‑times, and sleep‑related behaviours and beliefs.23
That’s because changing them is what lets the system relearn that bed is for sleep, and that sleep doesn’t need constant watching or protection.
Why naps and lie‑ins can backfire
When you’re exhausted, napping and lying in are completely understandable. The catch is how they affect the basic “physics” of sleep.
- Sleep pressure builds the longer you’re awake.2
- Daytime naps and long lie‑ins let that pressure out, so there’s less drive to sleep at night.2
- Spending more time in bed when you’re not sleeping lowers your sleep efficiency (the percentage of time in bed that you’re actually asleep).23
Clinical guidelines therefore recommend consolidating sleep and avoiding regular daytime naps while you’re working on insomnia, because those changes strengthen the link between bed and actual sleep. And for those who are afraid of how that sounds – it is temporary.
Clock‑watching and “sleep maths”
Clock‑watching feels like a small thing, but it can really pour petrol on the fire.
One experimental study found that people with insomnia who monitor the clock more at night also report higher arousal and more sleep‑related distress.4
A more recent clinical paper reported that time‑monitoring behaviour is linked with insomnia severity and with greater use of sleep aids.5
The loop is familiar to most people with insomnia:
- You look at the clock.
- You instantly calculate how little sleep you’ll get.
- Anxiety spikes, your body gears up, and sleep slips further away.
That’s why CBT‑I programmes often include unglamorous moves like turning the clock away or using an alarm without a visible display – to reduce a very specific insomnia-maintaining loop.24
There are many, many elements to how insomnia is perpetuated for any given individual – this often needs one to one work to tease out. Feel free to grab a chat with me to see how I can help.
