Cold Showers in the Morning: What They Do and What They Don't
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Cold showers in the morning are promoted as a fast way to wake up, boost energy and toughen up your immune system. Some of that has research behind it, and some of it is stretched well past what the studies found. This guide covers what a cold shower does in the moment, what the best evidence shows, what it can't do, who should be careful, and a gentle way to start if you want to try it.
The short answer: a cold finish to your morning shower is likely to make you feel more awake, and in the largest trial people who did it took fewer sick days from work. It didn't make them get sick less often, and most other benefits you'll see claimed are unproven. Cold showers won't fix poor sleep or replace enough hours in bed. If you're healthy and you enjoy it, it's a reasonable habit. If you have a heart condition or high blood pressure, check with your GP first.
What a cold shower does in the moment
Cold water on your skin is a shock to the system. A 2025 review of cold-water immersion trials describes an immediate burst of "fight or flight" activity, followed later by a calmer, recovery-type response. Inflammation markers actually rose straight after cold exposure and an hour later, a sign of the body's short-term stress response (source).
That jolt is what makes you feel alert. It's also why the first few seconds feel so unpleasant, and why it isn't for everyone.
What the best evidence shows
The study most often quoted is a large Dutch trial from 2016. More than 3,000 working adults were randomly assigned to finish their usual warm shower with 30, 60 or 90 seconds of cold water every day for 30 days, or to shower as normal (source).
| Outcome | What they found |
|---|---|
| Sick days off work | 29% fewer in the cold shower groups than in the control group |
| Number of days ill | No meaningful difference |
| Energy | Increased energy was the most commonly reported benefit |
| Quality of life | A small early improvement in mental wellbeing at 30 days that had faded by 90 days |
| Length of cold | 30, 60 and 90 seconds gave similar results |
So people didn't catch fewer bugs, but they seemed to push through them and miss less work. The authors noted important limits: everything was self-reported, there was no way to rule out a placebo effect, a fifth of people dropped out, and the volunteers were unusually healthy.
What cold showers can't do
The 2025 review, which pooled 11 trials and more than 3,000 people, found no clear effect on mood and only limited evidence for sleep, from a single study in a specific setting. Most trials were small, mostly in men, and looked at single exposures. The authors concluded that more robust evidence is needed before firm claims can be made about the benefits or safety.
That means a cold shower is not:
- A cure for tiredness. If you're short on sleep, the jolt wears off and the sleep debt remains. See can you catch up on sleep.
- A replacement for daylight. Getting natural light early in the day is one of the clearest ways to support your body clock (source).
- A treatment for any illness, including anxiety or depression.
Who should be careful
The cold shock is a stress on your heart and circulation. Be cautious and talk to your GP first if any of these apply:
- Heart disease, heart rhythm problems or high blood pressure.
- Poor circulation or conditions where your fingers and toes react badly to cold.
- Pregnancy.
- You feel faint, dizzy or very breathless under cold water. Turn it warm and stop.
In the Dutch trial, the most common side effect was feeling cold in the body, hands or feet afterwards. A small number of people reported muscle aches, itching or trouble sleeping. Cold showers are very different from swimming in cold open water, which carries extra risks and is best done with others around.
How to start gently
You don't need to stand under icy water for minutes. The Dutch trial found 30 seconds at the end of a normal shower worked as well as 90.
- Shower as usual with warm water.
- Turn it to cool for the last 15 to 30 seconds. Breathe slowly through it.
- Build to cold over a week or two, if you're enjoying it.
- Keep it to 30 to 90 seconds. Longer hasn't been shown to help more.
- Warm up afterwards with a towel and clothes, especially in winter.
Pair it with the habits that make mornings easier: a fixed wake-up time, light and a little movement. For more, see how to become a morning person and how to wake up early in winter.
Morning or evening?
A cold shower is a wake-up tool, so most people use it in the morning. Some people like a cool shower before bed in a hot Australian summer. If you do, keep it cool rather than icy, as a big jolt right before bed may leave you feeling more alert. For summer nights, see hot weather sleep tips.
When to see your GP
See your GP before starting if you have a heart or blood pressure condition. Also see your GP if you're relying on cold showers to get through the day because you're always exhausted, as that can point to a sleep problem or another health issue. This guide is general information, not medical advice.
Where the Sovune Nudge fits
We make the Sovune Nudge, a silent alarm wristband, so we're not neutral. A cold shower helps once you're up. The Nudge is about getting you up in the first place, without waking the house.
- Wakes you with vibration on your wrist, starting as a gentle tap and building through three intensity levels.
- Vibrates for a full minute per alarm, and you can switch it off sooner if you're already up.
- Water-resistant for everyday use. Showers and rain are fine, though not swimming or diving.
- Up to 14 days of nightly use per charge, rechargeable via USB.
It comes with a 30-day money-back guarantee.
Quick answers
Do cold showers really wake you up? Most people feel more alert straight afterwards, and increased energy was the most common benefit reported in the largest trial.
How long should a cold shower be? 30 seconds at the end of a warm shower is enough. In the Dutch trial, 30, 60 and 90 seconds worked about the same.
Do cold showers boost your immune system? Not in a proven way. People in the big trial took fewer sick days, but they weren't ill less often.
Can cold showers replace sleep? No. They can mask tiredness for a short time, but the sleep debt stays.
For every type of silent alarm compared, see our complete guide to vibrating alarms in Australia.