Morning cold plunge

What it is

A brief cold-water exposure in the morning: a plunge tub, a cold lake, or the last part of your shower turned to cold. Sessions are short, often 1–3 minutes.

What the research says

Cold-water research is mixed and many studies are small. Results depend a lot on water temperature, duration and who was studied.

• Alertness and mood. A review of 11 randomized studies found cold-water immersion may briefly improve how alert or good people feel. It doesn’t show a lasting benefit, and the studies used very different protocols. (Cain et al., PLOS ONE, 2025)
• Heart rate variability. Cold water clearly changes HRV in the moment, but most of that research is on diving and face immersion in water below 5 °C, not a home plunge. (Lundell et al., International Journal of Circumpolar Health, 2023)
• Right after lifting. Regular cold-water immersion at 15 °C or colder, used with a resistance-training program, was linked to smaller strength gains than training without it, across eight studies. (Malta et al., Sports Medicine, 2021) A separate review of eight studies found that immersion immediately after lifting may modestly blunt muscle growth, and rated that evidence fair to poor. (Piñero et al., European Journal of Sport Science, 2024) A short cold shower in the morning, away from a workout, is a different question.

How to try it

1. Start with a cold shower finish: 30 seconds of cold at the end of a normal shower.
2. Build up slowly over the first week, toward 1–3 minutes.
3. Never plunge alone in open water, and get out if you start shivering hard.
4. Do it at the same time each morning so day-to-day changes are easier to read.

Cold water puts a sudden load on the heart. If you have a heart condition or high blood pressure, ask a clinician first.