Health Advice



Don't rock your clock

By Michael Roizen, M.D. on

The actress Kim Cattrall says her battles with insomnia affect her "ability to think clearly. I can't grasp, hold on, to ideas, thoughts, even tasks." But your internal body clocks affect more than your mental powers. If you contend with insomnia, chronic stress, frequent jet lag, nighttime snacking, or an irregular work schedule you're increasing your risk for cancer, obesity, depression and metabolic diseases, such as diabetes.

What are your body clocks, aka circadian rhythms? The most well-known is the one that controls your 24-hour sleep-wake cycle. There are also 24-hour body rhythms that affect hormonal activity, body temperature, digestion and immune function. Then there's the master clock, the suprachiasmatic nucleus, which influences all of the other body clocks directly or indirectly. It's made up of around 20,000 nerve cells and receives input from the eyes -- as they perceive daylight and nighttime darkness, they tell your body's cells and brain chemicals to act accordingly.

Everyone's body clocks are slightly different, but one thing is true -- if you mess with them, they mess with you. For example, a study published in Science Advances shows that chronic circadian disruption makes mice more likely to develop lung cancer -- and that's likely in people, too.

Fortunately, you can harness your body clocks to improve your health: Aim for the same seven to eight hours of sleep nightly; avoid blue light (digital devices) for two hours before bedtime; sleep in darkness; get sunlight in early morning. And, if your job makes time-shifting inevitable, try Timeshifter's "Shift Work App."



Health pioneer Michael Roizen, M.D., is chief wellness officer emeritus at the Cleveland Clinic and author of four No. 1 New York Times bestsellers. His next book is "The Great Age Reboot: Cracking the Longevity Code for a Younger Tomorrow." Do you have a topic Dr. Mike should cover in a future column? If so, please email

(c)2022 Michael Roizen, M.D.

Distributed by King Features Syndicate, Inc.

(c) 2022 Michael Roizen, M.D. Distributed by King Features Syndicate, Inc.



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