Man resting with eyes closed in bath

Need More Zs? Try This Heat Exposure Protocol

There’s a reason a hot bath before bed is so popular.
By Rebekah Harding
May 13, 2024

We always hear that keeping your bedroom cool (around 65 degrees Fahrenheit) is ideal for sleep. But the right amount and timing of heat may actually improve your Zs. Cell biologist Rhonda Patrick, Ph.D, says you can take advantage of the sleep-inducing benefits of heat exposure therapy to get the best rest of your life. 

In a recent episode of her FoundMyFitness podcast, Patrick explains how deliberate heat exposure a couple hours before bed can improve slow wave sleep—the stage which supports growth, immune function, and memory. Getting enough slow wave sleep is important in staving off dementia and Alzheimer’s, says Patrick.

“It’s been my personal experience that heat exposure with appropriate cool down has helped me with aspects of my sleep,” Patrick says. 

Passive body heating (raising your body temperature without physical activity) 1 to 2 hours before bedtime may trigger sleepiness, according to a 2019 clinical review (1). But the three mechanisms that interest Patrick the most are the release of sleep-promoting hormones—growth hormone (GH), growth hormone-releasing hormone (GHRH), and prolactin—that are triggered by heat exposure. 

“Most GH secretion occurs in the initial phase of slow wave sleep, but conversely GH and GHRH have been shown to promote slow wave sleep,” Patrick explains. 

Want to get the most sleep benefits out of heat exposure? You’ll want to follow one of Patrick’s heat exposure protocols to a T. 

Rhonda Patrick’s Heat Exposure Protocols

In the sauna

“Regular sauna use is probably one of the most powerful stimuli that increases both growth hormone and prolactin,” Patrick says.

Temperature: 176 degrees Fahrenheit

Timing: 20 minutes, 1-2 hours before bed

Don’t want to head to the gym before bed? There are a variety of at-home saunas that you can use to boost your heat exposure game. 

In the bath

If you don’t have a sauna, draw a hot bath and “submerge as much of the body from shoulders down as possible,” Patrick says. 

Temperature: 104 degrees Fahrenheit

Timing: 20-30 minutes, 1-2 hours before bed

“For hot baths, you may need to add more hot water throughout to keep the temperature around 104,” Patrick says. “In that case, a thermometer may be helpful to monitor the temperature.”


Pro-tip: Cool off after

What you do after heat exposure is just as important as what you do during your 20-minute roast session. 

The initial effects of heat exposure may include increased wakefulness due to a rush of ATP, or cellular energy (2). This can make it harder to transition directly from the tub into bed for some shut-eye. 

Patrick recommends jumping in a cool shower to speed up the process.