Both, usually, and that is the honest answer. Anxiety makes it harder to sleep, and sleeping badly makes you more anxious the next day. By the time most people go looking for help, the two are locked together and the question of which came first has stopped being useful. The question worth asking instead is which one is keeping the cycle going right now, because that is what decides where treatment starts.
Key takeaways
- The relationship runs in both directions. Anxiety disrupts sleep, and poor sleep lowers your threshold for anxiety the following day.
- Insomnia is no longer regarded as merely a symptom of anxiety that resolves when the anxiety is treated. It frequently persists on its own.
- The practical test is what your mind does at 3am: if the worry is specifically about not sleeping, insomnia is doing the driving.
- CBT-I remains effective for insomnia in people who also have anxiety, and treating the sleep often eases the anxiety.
- If anxiety is present through the day, independent of sleep, both need addressing.
How each one feeds the other
Anxiety to insomnia is the direction everyone recognises. Anxiety is a state of anticipatory threat, and the physiology that goes with it, raised heart rate, muscle tension, an alert and scanning mind, is close to the opposite of what sleep onset requires. Worry is also cognitively engaging in a way that keeps you oriented outward when sleep needs you to disengage.
Insomnia to anxiety is the direction people underestimate. A night of fragmented sleep reduces your capacity to regulate emotion the next day. Things that would ordinarily be manageable feel larger, threat is easier to detect and harder to dismiss, and your tolerance for uncertainty drops. You then arrive at the following bedtime with more to be anxious about, and with the added anxiety of knowing how last night went.
There is good prospective evidence for the sleep-comes-first direction in mood disorders specifically. A meta-analysis of twenty-one longitudinal studies found that people with insomnia who were not depressed had roughly double the risk of later developing depression, with an odds ratio of 2.60 (95% confidence interval 1.98 to 3.42). We are quoting that carefully: it is a depression finding, not an anxiety one, and we are not going to transfer the number across. What it establishes is that insomnia is not merely a downstream symptom. It carries its own forward risk.
The most important shift in how this is treated
For a long time, insomnia occurring alongside a psychiatric condition was labelled "secondary" and the logic followed: treat the anxiety, and the sleep will sort itself out.
That turned out to be wrong often enough to change practice. Insomnia frequently persists after the anxiety improves, because by then it is being maintained by its own machinery: conditioned arousal in the bedroom, compensatory behaviours like long lie-ins and early bedtimes, and anxiety about sleep itself, which is a distinct thing from generalised anxiety.
The practical consequence is that insomnia usually deserves direct treatment rather than waiting for the anxiety to clear. Cognitive behavioural therapy for insomnia retains its effectiveness in people who also have anxiety or depression, which is precisely why it is not held back until the psychiatric picture is resolved.
How to tell which one is in the driving seat
Nobody can settle this from an article, but these distinctions are what a clinician is listening for.
Insomnia is likely the main driver if:
- The worry at night is mostly about sleep: hours remaining, how tomorrow will go, whether tonight will be another bad one.
- You sleep noticeably better away from your own bed, on holiday, or somewhere unfamiliar.
- Daytime anxiety tracks your sleep. Good night, manageable day.
- You feel calm during the day and wired the moment you get into bed.
Anxiety is likely the main driver if:
- The worry at night is about your life, not your sleep, and it is the same content that occupies you during the day.
- You feel tense and on edge regardless of how you slept.
- There are physical symptoms through the day: chest tightness, a churning stomach, restlessness, being easily startled.
- You avoid situations because of anxiety, or it is affecting work or relationships.
Both are in play if you recognise most of both lists, which is the most common outcome and is not a diagnostic failure. It just means the plan addresses both.
A short screening question set called the GAD-2 asks how often over the past two weeks you have felt nervous or on edge, and how often you have been unable to stop or control worrying. A score of 3 or more is the usual threshold for looking further. It is a prompt to investigate, not a diagnosis.
What treatment usually looks like
Start with the sleep in most cases. CBT-I is first-line for chronic insomnia and it works on the arousal and conditioning that keep the cycle running. It includes the behavioural work covered in stimulus control, plus sleep restriction and the cognitive work of dismantling beliefs about sleep that generate anxiety on their own. Details in CBT-I in South Africa.
Treat the anxiety in its own right where it warrants it. Where anxiety is present independent of sleep, psychological therapy is the mainstay, and psychology or psychiatry review is appropriate. Decisions about medication belong in a consultation with someone who has taken a full history, not in an article, and we are not going to make recommendations about them here.
Expect the two to improve together. Because the loop runs both ways, progress on one side usually shows up on the other. That is the useful part of a vicious cycle: it can be run in reverse.
Be careful about what you reach for in the meantime. Alcohol is the most common self-directed answer to both problems and it is one of the worst, because it sedates the first half of the night and fragments the second. Sedating medication has a limited short-term role at most, decided in consultation, and it does not treat either condition.
If anxiety or low mood is the larger problem, the South African Depression and Anxiety Group runs a 24 hour Suicide Crisis Helpline on 0800 567 567, and a general mental health line on 011 234 4837 (8am to 8pm, seven days a week).
Frequently asked questions
Can anxiety cause insomnia? Yes. Anxiety produces the physiological and cognitive arousal that directly opposes sleep onset, and worry keeps the mind engaged when sleep requires disengagement. The relationship also runs the other way, which is why the two so often present together.
Can insomnia cause anxiety? Yes. Poor sleep reduces your capacity to regulate emotion, lowers your tolerance for uncertainty and makes threat easier to notice the following day. Prospective research also shows insomnia carries forward risk for mood disorder, with insomnia roughly doubling the risk of later depression.
Should I treat my anxiety or my insomnia first? Often both together, and insomnia usually deserves direct treatment rather than waiting. The older assumption that treating anxiety would resolve the sleep problem turned out to be unreliable, because insomnia becomes self-maintaining. CBT-I works even when anxiety is present.
How do I know if my anxiety needs professional treatment? If anxiety is present most days independent of how you slept, if it comes with physical symptoms through the day, or if it is affecting your work, relationships or the things you are willing to do, it warrants assessment in its own right rather than being treated as a sleep problem.
Will treating my insomnia make my anxiety better? Frequently, yes, because the cycle runs in both directions and improving sleep restores some of the emotional regulation that poor sleep erodes. How much it helps varies between people, and where an anxiety disorder is present it will usually need addressing on its own terms as well.
This article is educational and is not a diagnosis or a substitute for medical advice. Slumbr does not provide emergency care. If you are in crisis, seek urgent in-person help.
Not sure whether it is the anxiety or the insomnia? Take the free Slumbr Sleep Pattern Assessment™, which screens for anxiety and mood alongside the insomnia phenotypes. Or book an online consultation with a specialist physician.