STORY AND PHOTO BY KAREN BOSSICK

The key to a long life lies in one simple practice: Getting between seven and nine hours of sleep each night.

That’s what Matthew Walker, a self-proclaimed ambassador of sleep, told those attending the Sun Valley Wellness Festival and Conference this week.

“The shorter you sleep, the shorter your life,” he told those attending the conference virtually and at the Argyros Theater in Ketchum.

Those who sleep four hours a night experience a 70 percent reduction in the natural killer cells that stave off disease and infection. And this happens quickly—after one sleep-deprived night. One week of poor sleep can render someone prediabetic. And the link between sleep and cancer is so strong that the World Health Organization now classifies shift work as a probable carcinogen.

“We see a 24 percent increase in heart attacks when people lose an hour of sleep in spring due to daylight savings time,” Walker said. “We see a 21 percent reduction in the fall when they get an extra hour.”

A professor of neuroscience and psychology at the University of California-Berkeley, Walker came to America from his native Britain to spend two years studying sleep. That was 20 years ago.

He is now the director of the Center for Human Sleep Science at UC Berkeley. And his book “Why We Sleep,” is a best seller, pointing to a link between sleep deprivation and Alzheimer’s, heart disease, cancer and depression.

It’s been known for a while that people’s memories worsen as their sleep worsens with age, Walker said. But recently scientists discovered a connection between Alzheimer’s disease and poor sleep.

“That’s exciting because we may be able to do something about it,” he said. “It appears that stimulation to the brain can almost double the amount of benefit you get from sleep.  If we can restore the quality of sleep, we may be able to restore memory.”

Older people aren’t the only ones who should worry about their quality of sleep. High school and college students deciding to pull an all-nighter before finals might want to rethink that practice.

Walker described putting an all-nighter to the test in an experiment in which one group got eight hours of sleep and the other was forced to stay awake. Lab techs took snapshots of each person’s brain activity in an MRI while they were fed new facts.

Those who’d had a full night of sleep saw lots of healthy learning-related activity. Those who were sleep deprived didn’t exhibit a significant signal at all.

“It was almost as if sleep deprivation shut down their memory inbox. Any new incoming files were rejected,” Walker said.

But what can those who would kill for a good night’s sleep do?

• Exercise regularity in your sleep practice, Walker said. Go to bed at the same time and wake up at the same time. And, “wake up” means get out of bed.
• Keep your bedroom cool. The best bedroom temperature is about 65 degrees, said Walker, who admitted to sticking rectal probes in people to determine how their core temperature affects awakening.

  Your body needs to drop its core temperature two to three degrees Fahrenheit to initiate sleep and stay asleep. Hot baths or showers at bedtime work because the blood races to the surface of the skin, the skin acts as a radiator and the core body temperature plummets.

  Walker himself insists on eight hours of uninterrupted sleep. But he says other individuals’ optimal sleep time can range between seven and nine hours. Dip below seven hours and researchers can measure impairments in brain and body. The number of people who can survive on less than six hours a sleep of night is zero, he added.

  “Sleep is not an optional lifestyle luxury. It’s a non-negotiable biological necessity. It’s your life support,” he said. “Sleeplessness is an epidemic that’s fast becoming one of the great challenges our world faces. It’s time to reclaim our sleep.”

  WHAT ABOUT NAPS AND SLEEPING PILLS AND CANNIBIS?

• Walker said there might be a case to be made for a nap. But a nap that’s too long or too close to bedtime is like snacking before dinner. It takes the edge off your sleep appetite.
• Those who take sleeping pills are mistaking sedation for sleep, he said. Take too many and you can count on rebound insomnia. You also lose confidence in your own ability to sleep.

  Far better is cognitive behavioral therapy that helps the insomniac identify and replace thoughts and behaviors that cause or worsen sleep problems with habits that promote sound sleep.

• Sleep restriction, in which you reduce the amount of time you spend in making you more tired the next night, might also help.

  “If you have only 15 minutes to work out, you go all out. Sleep is the same way. Retrain your system by cutting your sleep time to five hours. Then back up to 5.5 hours, then 6 hours…until you’ve reached maximum efficiency.”

• Avoid alcohol in the evening. Even a late afternoon nightcap affects sleep.
• The THC in marijuana does not help sleep because dependency builds quickly and you need more and more to sleep. Stop using and you get a horrible rebound insomnia, Walker said. THC also blocks rapid eye movement or REM sleep, which is essential for brain functions, emotional health and the release of growth hormones.

There isn’t a lot of data on CBD, but it may be beneficial at doses of 50 mg. as it addresses anxiety

iPads viewed too close to bedtime contribute to sleeplessness and a marked reduction in REM sleep. Lights and devices of all types make it feel more like it’s 5 p.m. than bedtime. An hour before bedtime turn off most of the lights in your home and you’ll be surprised how sleepy that makes you, Walker said.

“The principal cause of insomnia is anxiety and stress. For stress I’m a big advocate of medication. I also advocate breathing exercises and other ways to minimize anxiety,” he said. “I’m not nuts about sleep devices except sleep rings. When you go to sleep, you tend to take things off.”

TUNE INTO THE SUN VALLEY WELLNESS FESTIVAL SPEAKERS

Virtual Festival passes, available for $95, allow access to all speaker presentations, guided meditations and movement classes through July 31. To purchase go to https://www.sunvalleywellness.org/tickets-and-passes