IN 2010’s “Hot Tub Time Machine,” John Cusack, Rob Corddry and Craig Robinson play three bummed-out friends who go to a ski resort. When they juice up their hot tub’s controls (don’t ask) with an illegal Russian energy drink, it transports them back to 1986. Not exactly the relaxing soak they were expecting. But there’s no reason why you can’t indulge in the benefits of a good soak in the here and now — and fall asleep faster and enjoy better sleep quality.

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A new analysis of the power of baths, published in Sleep Medicine Reviews, found that getting a good soak one to two hours before bedtime in a warm, but not too hot, tub actually lowers your core body temperature by expelling heat through your extremities.

In the evening, that happens naturally (if all is working right) and encourages sleep. Your core temperature then rises in the morning, acting as a natural alarm clock. The bath simply makes sure that process works for you.

The optimal water temperature: 104 to 109 degrees. A good temperature for a cup of coffee is 140 degrees, so it’s considerably cooler than that! And you don’t have to soak until your fingertips wrinkle; the researchers say 10 minutes will do the trick.

A couple of cautions: If you have heart disease, make it comfortably cooler, and once you’re out of the bath (or hot tub or Jacuzzi) and headed to bed, make sure the room is dark and all digital screens are off. Sweet dreams.

Mehmet Oz, M.D., is host of “The Dr. Oz Show,” and Mike Roizen, M.D., is chief wellness officer and chairman of Wellness Institute at Cleveland Clinic. To live your healthiest, tune into “The Dr. Oz Show” or visit