Hotwired: How the Hidden Power of Heat Makes Us Stronger

From the #1 New York Times bestselling coauthor of Outlive comes a radical exploration of the science of heat adaptation and sweat therapy to tap into the evolutionary superpowers that we’ve forgotten we possess.

What if the key to thriving in a hotter world isn’t avoiding the heat—but harnessing it?

In Hotwired, bestselling author and science journalist Bill Gifford takes readers on a fascinating exploration of the power of heat to improve our performance and our health. Combining cutting-edge science, personal discovery, and practical insights, Gifford reveals how heat adaptation and heat therapy such as sauna can make us healthier, stronger, and even happier, by unlocking the body’s built-in tools to promote longevity and resilience.

Through innovative research in evolutionary biology, physiology, and thermoregulation, Gifford uncovers how humans evolved to excel in sweltering conditions—and how we’ve lost touch with this ancient advantage. He plunges into the steamy world of Finnish saunas, serves as a test subject in cutting-edge heat labs, and tackles a grueling 100-mile bike ride under the blazing Texas sun—to show how temperature extremes can expand our physical and mental limits. He even explores how infrared sauna therapy could fight depression more effectively than medication—and how many people are rediscovering the power of communal wellness through the use of social sauna.

Whether you’re looking to perform better, extend your lifespan, adapt to a warming planet, or tap into the human connection that forms when we sweat together, Gifford reveals the incredible benefits of reawakening your body’s natural adaptability to heat and cold. You’ll discover how sweat is more than a cooling mechanism; it’s central to peak performance. Rather than hiding from the heat, we should confront it, to discover our untapped potential for physical and mental resilience. We were born to sweat, after all.

Hotwired lays out how short-term discomfort transforms into long-term power. It’s a thrilling call to reimagine heat—not as a threat, but as a tool for survival and strength.

© 2026 Harper Wave (Audiobook): 9780063448070

Release date

Audiobook: 17 March 2026