Anxious or low? Check your body before your head

"I feel anxious and nothing is wrong"

It's an ordinary week and nothing has gone wrong. Your heart is a little quick, your mind won't settle, and by evening there's a flat, grey feeling on top.

Is something wrong with me?

The answer you get is often a story. It's your childhood, your job, your attachment style. Sometimes it is.

But plenty of people end up changing something small and physical, like cutting a third coffee or sleeping an hour more, and say they felt different within days.

That is anecdote, not proof. I wanted to see how much of it holds up. So this is a short tour of the physical basics, what the research says about each, and where the evidence runs out.

One boundary first. I'm talking about feeling anxious or low, not about a diagnosed condition. If what you have is a diagnosis, or you suspect one, this is a side dish and not the meal.

What's going on in your body

Anxiety is partly a body event. Your heart rate, your breathing and your alertness are all chemistry and wiring, and each of them can be pushed around by things you do every day.

Think of a dial rather than a switch. Your baseline sits somewhere. A stimulant nudges it up. A bad night's sleep nudges it up. A day with no movement skips one of the better-supported ways to bring it down. None of these is the whole story. But stacked together, they can turn an ordinary stressful week into something that feels like a crisis.

The useful part is that the dial has a few handles you can reach. Before you decide the problem is your personality, it is worth checking them. Here is what each one has going for it.

What the research says

Caffeine does what you'd expect, and more so at high doses

A meta-analysis by Liu and colleagues (2024) pooled 14 studies and 546 healthy people. Caffeine was linked to higher anxiety scores overall. Low doses had a moderate effect, and the effect was much larger above about 400 mg a day, a few strong cups. The authors note that the studies differed in how they measured anxiety, so I'd treat the exact numbers loosely.

For people who are already prone to panic, the picture is sharper. Klevebrant and Frick (2022) reviewed ten placebo-controlled studies of caffeine challenges, using doses of 400 to 750 mg. About 54% of patients with panic disorder had a panic attack after caffeine, against under 2% of healthy controls. That is a clinical group, not a general one, and the doses were big. The authors also say little is known about doses below 480 mg.

Caffeine also leaks into the night. Drake and colleagues (2013) gave volunteers 400 mg at bedtime, three hours before, or six hours before, and compared it with placebo. Even the six-hour dose cut total sleep time. So a late-afternoon coffee can still be in your system when you try to sleep.

Sleep is the one I'd check first

Ben Simon and colleagues (2020) did something simple and revealing. They found that a night of sleep loss raised next-day anxiety, and that this was linked to impaired activity in the brain's medial prefrontal cortex and its connections to emotion-related regions. They also found that, across the population, even modest night-to-night drops in sleep predicted higher anxiety the next day.

That second finding matters most. You don't need to be sleeping three hours a night. Losing a bit was linked with more anxiety the next day. That is a link, not proof of cause, but it is a cheap one to test.

Movement has the biggest body of evidence

Singh and colleagues (2023) pulled together 97 reviews covering over a thousand trials and more than 128,000 participants. Physical activity reduced anxiety symptoms with a medium-sized effect (a median of about -0.42 in standardised terms), and similar effects for depression and general distress. Higher-intensity activity tended to help more. Shorter programmes tended to show bigger effects than longer ones.

There is a caveat the authors state plainly. Most of the underlying reviews were rated critically low on quality. So I'd say the direction is consistent and the size is probably real but not precise. It is also hard to run a blinded exercise trial, since everyone knows if they're jogging.

Slow breathing helps a little, and the hype is ahead of the data

Fincham and colleagues (2023) meta-analysed 12 randomised trials on stress and 20 on anxiety. Breathwork was associated with lower anxiety, with a small-to-medium effect (g = -0.32). The authors then urge caution. Most studies had a moderate risk of bias, and they warn of a "miscalibration between hype and evidence."

So breathing exercises are cheap, safe and probably useful. They're not a miracle, and the abstract doesn't single out one technique as the best.

Omega-3: possible, mixed, and dose-dependent

Su and colleagues (2018) analysed 19 trials with over 2,200 participants. Omega-3 supplements were associated with a modest reduction in anxiety symptoms (Hedges' g = 0.37). But the benefit showed up only in studies using at least 2,000 mg a day, and it was larger in people with a clinical diagnosis than in people without one. The authors call for better trials in people whose main problem is anxiety. For someone who is just feeling off, this is thin.

Vitamin D: the supplement result is a miss

The most careful test I found is the VITAL-DEP trial (Okereke et al., 2020). It gave 18,353 adults aged 50 or older either 2,000 IU of vitamin D3 a day or a placebo, for a median of 5.3 years. Depression risk and mood scores did not differ between the groups. The authors say the findings do not support vitamin D3 to prevent depression in adults. That trial was about depression, in adults aged 50 and over. I found no solid trial evidence that vitamin D supplements reduce everyday anxiety.

Myths and gaps, labelled

Rooibos tea calms you down. I searched PubMed for human trials of rooibos and anxiety and found none. I can't point to where the idea started. It's a pleasant, caffeine-free drink, and swapping it in for a late coffee has real logic. The calming effect itself is unproven.

Green tea's L-theanine settles anxiety. The best review I found, by Camfield and colleagues (2014), covered 11 trials. It found moderate effects of combined caffeine and L-theanine on alertness and attention within two hours. Its abstract doesn't report a clear anxiety result. So "alert and focused" is supported. "Calm" is not shown there.

Multivitamins fix your mood. I found no strong trial evidence behind this as a general claim, so I've left it out.

Food. I haven't cited anything on diet here, because I didn't verify a study I could stand behind. It's probably worth a separate piece.

What to try

Treat this as a two-week experiment, not a lifestyle overhaul. Change one thing at a time so you can tell what moved.

1. Move your last coffee earlier. Set a cutoff around noon, or at least six hours before bed, in line with the Drake findings. Keep your total under about 400 mg, which is a ceiling to stay beneath rather than a target. If you suspect you're sensitive, try dropping a cup for a week and see.

2. Protect your sleep window. Pick a wake time and hold it, even at weekends. The research links even small nightly losses to more anxiety the next day, so a regular 30 extra minutes is worth trying.

3. Move on purpose. A brisk walk counts. If you can push the pace a bit, the evidence leans toward harder being better, within what your body can safely handle. Aim for most days of the week.

4. Slow your breathing for five minutes. Breathe in through your nose, slowly and comfortably. I'm not claiming a best technique or a magic ratio, because the review doesn't name one.

5. Skip the shelf of pills for now. Omega-3 is a maybe at high doses. Vitamin D didn't help mood in the best trial, in adults aged 50 and over. If a blood test shows you're low in something, that's a conversation with a doctor, not a guess.

If this lasts more than a couple of weeks, or it starts getting in the way of work, sleep, relationships or ordinary life, see a doctor. That isn't a failure of the experiment. A doctor can check for physical causes and point you to treatment that fits what is actually going on.

If you ever feel unsafe, or think about harming yourself, contact a doctor or a crisis line in your country straight away.

If you only do one thing, do the boring one. Pick a time tonight, set an alarm for tomorrow morning, and keep both for fourteen days. Sleep is the cheapest handle to test.

Sources

• Ben Simon, E., Rossi, A., Harvey, A. G., & Walker, M. P. (2020). Overanxious and underslept. Nature Human Behaviour, 4(1), 100-110. https://doi.org/10.1038/s41562-019-0754-8
• Camfield, D. A., Stough, C., Farrimond, J., & Scholey, A. B. (2014). Acute effects of tea constituents L-theanine, caffeine, and epigallocatechin gallate on cognitive function and mood: a systematic review and meta-analysis. Nutrition Reviews, 72(8), 507-522. https://doi.org/10.1111/nure.12120
• Drake, C., Roehrs, T., Shambroom, J., & Roth, T. (2013). Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of Clinical Sleep Medicine, 9(11), 1195-1200. https://doi.org/10.5664/jcsm.3170
• Fincham, G. W., Strauss, C., Montero-Marin, J., & Cavanagh, K. (2023). Effect of breathwork on stress and mental health: a meta-analysis of randomised-controlled trials. Scientific Reports, 13, 432. https://doi.org/10.1038/s41598-022-27247-y
• Klevebrant, L., & Frick, A. (2022). Effects of caffeine on anxiety and panic attacks in patients with panic disorder: a systematic review and meta-analysis. General Hospital Psychiatry, 74, 22-31. https://doi.org/10.1016/j.genhosppsych.2021.11.005
• Liu, C., Wang, L., Zhang, C., Hu, Z., Tang, J., Xue, J., & Lu, W. (2024). Caffeine intake and anxiety: a meta-analysis. Frontiers in Psychology, 15, 1270246. https://doi.org/10.3389/fpsyg.2024.1270246
• Okereke, O. I., Reynolds, C. F., Mischoulon, D., et al. (2020). Effect of long-term vitamin D3 supplementation vs placebo on risk of depression or clinically relevant depressive symptoms and on change in mood scores: a randomized clinical trial. JAMA, 324(5), 471-480. https://doi.org/10.1001/jama.2020.10224
• Singh, B., Olds, T., Curtis, R., et al. (2023). Effectiveness of physical activity interventions for improving depression, anxiety and distress: an overview of systematic reviews. British Journal of Sports Medicine, 57(18), 1203-1209. https://doi.org/10.1136/bjsports-2022-106195
• Su, K.-P., Tseng, P.-T., Lin, P.-Y., et al. (2018). Association of use of omega-3 polyunsaturated fatty acids with changes in severity of anxiety symptoms: a systematic review and meta-analysis. JAMA Network Open, 1(5), e182327. https://doi.org/10.1001/jamanetworkopen.2018.2327