Is cold exposure (like ice baths) good for improving sleep?
Cold exposure can help some people fall asleep faster by lowering core body temperature, but ice baths too close to bedtime may increase alertness and stress hormones.
Summary
Research supports the idea that lowering core temperature promotes sleep onset. Mild cooling (cold showers, cool rooms) can help. However, ice baths activate the sympathetic nervous system, which may be counterproductive if done late in the evening.
Cold exposure has exploded in popularity, with athletes, biohackers, and wellness enthusiasts using it for recovery and stress resilience. But does it actually help with sleep?
To answer this, we need to separate mild cooling from intense cold exposure.
- The Science of Temperature and Sleep
Core body temperature naturally drops 1–2°F before bedtime. Research published in Sleep Medicine Reviews shows this drop is one of the primary biological signals that helps the body transition into sleep. Techniques that lower body temperature—such as warm baths or cool environments—can help accelerate sleep onset.
- Mild Cooling Can Improve Sleep
Mild cooling methods like:
cool showers
ice packs on the forehead
cooler bedroom temperatures (60–67°F recommended by the CDC)
…have been shown to improve sleep onset and sleep depth.
- Ice Baths: A Different Story
Ice baths trigger:
adrenaline
noradrenaline
dopamine
cortisol
sympathetic nervous system activation (“fight or flight”)
A study from PLOS One found that cold-water immersion increased sympathetic activity for up to an hour afterward.
This is not ideal before bed.
- Benefits May Still Exist When Timed Correctly
If cold plunges help someone regulate stress or improve their workouts, they may indirectly help sleep if done earlier in the day. Most experts recommend doing ice baths:
in the morning (dopamine surge)
before training (alertness)
at least 4–6 hours before bed
Conclusion
Mild cooling helps sleep. Cold plunges close to bedtime likely hurt sleep.
For sleep, choose cool rooms—not ice baths.