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Cryotherapy, floating chambers, NormaTec boots, infrared saunas, even Tom Brady–branded pajamas—science writer��Christie Aschwanden��tried it all while��researching��her new book����($28, W.W. Norton). (She did, however, skip vinotherapy,��the red-wine baths that .)��

But in a book that’s littered with insights into trendy recovery methods, you’ll find few endorsements. Instead, Aschwanden��advocates for common sense over flash, arguing��that, whether it’s a question of��getting more sleep or drinking when we’re thirsty,��our own bodies may��be the best recovery tools we have. “The fact that a whole industry has popped up to help healthy��people find ways to feel anxious about their bodies seems like a statement about the weird times we live in,” she writes. “Learn to read your own body and pay attention to what it’s telling you.” Below, we’ve rounded up five key��lessons at the heart of the book.

Stay Thirsty

What to drink during exercise,��and how much, is an ongoing��debate among athletes and health professionals.��While daily water-intake recommendations vary (the National Institute of Health ��that men consume three liters per day��and women 2.2 liters), athletes are invariably told to drink at every opportunity. This hydration preoccupation—often��prompted��by science of limited rigor and fueled by marketing from sports-drink��companies—has��lead to��people drinking even when they’re not thirsty, especially when working out. And��according to Aschwanden, that could be a big problem. “The body is highly adapted to cope with losing multiple liters of fluid,” she writes.

In fact, the evidence cited in her book shows that drinking too much water��poses a much greater risk than drinking too little. Overhydration can��lead to blood-sodium levels becoming diluted to dangerous and even fatally low concentrations (a condition known as hyponatremia). This became a recurring problem, for example, at the Comrades Marathon—a famous 90-kilometer race��in South Africa—after it added water stations for the first time in 1981. “There’s never been a case of a runner dying of dehydration on a marathon course,” recounts Aschwanden. “But since 1993, at least five marathoners have died from hyponatremia that developed during a race.” Drinking when thirsty, she advises, is the much better approach than wrought water consumption.

Skip the Ice

Icing postworkout��became a mantra of sports science after physician Gabe Mirkin coined the popular term RICE (rest, ice, compression, elevation) in 1978, and the recovery tool continues today in marathon medical tents and professional locker rooms.��Ice is meant to slow blood flow, which reduces inflammation and pain. But, it turns out, that also can be counterproductive, as it inhibits the rebuilding of muscle��and the restoration process. “Instead of promoting healing and recovery,” Aschwanden writes,��“icing might actually impair it.” And that’s led to a growing backlash against icing, which��. Instead of rushing to the cold stuff, Aschwanden advises athletes to wait it out and leave time for the body to heal.

Know Your Limits

In her former life, Aschwanden was an elite nordic skier, racing with Team Rossignol��in Europe and North America.��Every season, she remembers, followed��roughly the same pattern: After intense preparation, she would excel in her first few races. Then, as the months went on, she’d invariably come down with an injury, cold, or another ailment that would cut her performance short. Looking back, Aschwanden attributes her crashes in large part to fatigue from overtraining. “I needed less training than most athletes to reach and maintain peak conditioning,” Aschwanden writes. “But I did not appreciate that I also needed more rest and recovery.” Overtraining��syndrome is an increasingly recognized problem��that has led to the decline of many endurance athletes’��careers. To avoid pushing the body beyond its limits, Aschwanden suggests that athletes keep an eye out for personal signs of fatigue when training. Hers is a sore throat, but other indicators could include weight fluctuations, mood changes, or coming down with a bug.

Let Go of FOMO

Fear of missing out��is a common theme of Aschwanden’s book. Whether it’s a dietary supplement or an infrared sauna, she writes that many people try a new recovery technique simply��because other people around them are doing it. While that’s probably not harmful, she concludes,��any positive effect may just��be a placebo. “Many popular modalities strike me as sort of pacifiers,” she writes. “They won’t actually resolve anything, but they give you something to do while nature takes its course.”��If trying a new, unproven recovery method makes you feel better and more confident, great, she argues, but they almost certainly aren’t necessary.

Make Sleep King

One exception to Aschwanden’s��general skepticism is sleep.��“Insofar as there exists any magical secret for recovery, sleep is it,” she says. “The benefits of sleep cannot be overstated. It’s hands down the most powerful recovery tool known to man.” Beyond contributing to��lower testosterone levels and a suppressed immune system, a lack of sleep can also be tantamount to “showing up to the game drunk,” she writes. The right amount of sleep��for each person is—like many things in the book—subjective. Citing sleep scientist Amy Bender, Aschwanden writes that athletes should sleep when their body tells them to (that includes afternoon naps)��and shouldn’t stress out over one night of bad sleep. Instead, Bender advises people to “think of their sleep in terms of a weekly budget. Focus on your weekly need��rather than being concerned about eight hours every single night.”

So��when you’re choosing between extra sleep or that extra workout, she says you’re likely better off sleeping in—which is probably the best news of all.

is available��February��5 from W.W. Norton.��