As a neuroscientist and director of the Sleep and Cognition Lab at University of California, Irvine, Sara C. Mednick, PhD, would never tell you to skimp on sleep. The seven to eight hours you spend in bed every night are the ultimate restorative journey, as your brain leaves conscious thought behind and begins sorting through the day’s clutter. Memories are consolidated…energy stores replenished…hormone levels regulated…and much of the cellular wear and tear that naturally occurs during 16 or so hours of living is repaired.
But what if Dr. Mednick told you that you could reap those benefits during the day while you’re awake? That in addition to sleep, you can rejuvenate your brain, heart, muscles and more by exercising a certain way…eating a certain way…breathing a certain way? You can do that by tapping into the power of your body’s restorative systems using the downstate.
Healthy brains are surprisingly active during sleep, switching on and off in one-second periods called upstates, when brain activity is high…and downstates when it’s low. Sleep researchers believe that sleep’s restorative benefits emerge from these lightning-fast downstates.
Dr. Mednick has taken the sleep research concept of restorative sleep that takes place during deep, non-rapid eye movement (NREM) sleep and flipped it on its head to describe any time deep rejuvenation takes place. The average person’s upstate is when life activities require energy, focus, action and mobilization of mental and physical energy…and so the downstate is when our metaphorical tanks are refilled. That recharging takes place during meditation, while spending time in nature, while engaging in heart-pumping exercise and while spending quality time with loved ones. These healthy activities trigger hormonal and chemical cascades similar to the ones that occur during deep sleep.
Downstate-boosting activities promote autonomic balance—a healthy balance between the sympathetic nervous system (the fight-or-flight response that kicks in not just during moments of stress but whenever we think or act)…and the parasympathetic nervous system (the rest-and-digest system that calms us, decreases inflammation, and supports mental and emotional processing). Modern-day life—full of work pressures, family responsibilities and general stress—has most people tipped into autonomic imbalance. Their sympathetic branch revs all day long and even at night, with little time spent in rejuvenation mode. This imbalance is responsible for the lion’s share of premature aging, including deteriorating memory and immunity, heart disease, obesity and more.
Anytime you engage in an activity that balances your autonomic nervous system, you are harnessing the power of the downstate. Examples…
Exercise: During a challenging workout, your sympathetic nervous system revs up, increasing heart rate, powering muscles and more. After the workout, the parasympathetic system takes over to reverse those processes and bring you back to baseline—your heart rate slows, temperature drops and muscles relax. This parasympathetic recovery floods cells with restorative nutrients…lowers levels of the stress hormone cortisol…and triggers production of brain-derived neurotrophic factor (BDNF) and other neuroprotective hormones that stimulate the growth of new brain cells.
Deep breathing: You’ve likely heard that deep breathing helps relieve stress, but breathing in a specific way—about 10 to 12 seconds per breath, five to six breaths per minute—not only is relaxing, it also promotes autonomic balance by stimulating the vagus nerve, the conductor of the orchestra that is our parasympathetic nervous system.
Regular exercise and slow, deep breathing also balance the autonomic nervous system by improving heart-rate variability (HRV), the amount of variation between heartbeats. Most people think the heart beats like a metronome, with the exact same amount of milliseconds between beats. But there’s variation, and that’s a good thing. People who have high HRV, which is desirable, have more variation when it comes to the timing between heartbeats, although the variation is subtle. This sign of autonomic balance is linked with everything from enhanced memory and stress management to reduced rates of heart disease, diabetes and obesity. Unfortunately, HRV diminishes as we age. The timing between heartbeats becomes more uniform. That is indicative of the body becoming less tolerant of stress and is linked with many chronic health conditions. It happens for several reasons…
The 50-and-older set is significantly less likely to dedicate time to downstate-regulating activities. In a 2021 study by researchers at Florida Atlantic University, 55% of adults over age 60 said that they were less physically active than they had been two to three years prior. And 40% of Americans over age 75 are entirely inactive.
Older adults spend less time in nature. Most US adults spend five or fewer hours a week in nature.
And they spend more time alone. Nearly one-quarter of adults ages 65 and up are considered socially isolated.
Statistics like these are the main reason that aging seems to come with dramatic dips in physical, mental and cognitive functioning—people stop taking proactive steps to stimulate their downstate.
Not only do older adults tend to stop engaging in these daytime downstate activities, but their sleep quality suffers with every passing year. Once people hit their 40s, the time spent in slow wave sleep (SWS) naturally reduces. This is unfortunate because all the vital processes occur during SWS. Stress hormones pause while growth hormone and other hormones critical for muscle, organ and tissue repair, immune and metabolic function and inflammation control are released. The parasympathetic nervous system is never as strong as it is during SWS, which is why so much restoration happens here in our 20s and 30s…only to peter out as we get older. Good news: Engaging in downstate activities during the day can help make up for the natural loss in SWS.
Recent study: Young people and seniors were hooked up to electrodes to measure their brain activity and HRV as they move through the stages of sleep. In healthy young adults, there are giant increases in parasympathetic activity as they move from lighter to deeper sleep, and their HRV skyrockets. But in participants age 60 and up, there’s basically a flatline between their waking HRV and sleeping HRV. Simply by virtue of age, they fail to have any meaningful downstate recovery while they sleep.
Sleep is the ultimate downstate supporter. But here are other ways to improve your HRV and show your downstate some love during waking hours…
Exercise for 30 minutes at least three times a week. Make your workouts challenging—an easy walk won’t boost sympathetic activity enough to initiate a significant parasympathetic rebound. Schedule these workouts for the mornings—that gives your nervous system the time it needs (about a day) to fully recover, leading to HRV benefits.
Stop eating by 8 PM. Our digestive organs prefer to be in rest-and-digest mode overnight. Snacking at 10 pm kickstarts your sympathetic nervous system. This is why eating late at night makes it tricky to fall asleep—you are asking your energy-production centers to power on, even though you want your brain to power off.
Limit eating to 12, 10 or even eight hours a day. When you shorten your eating window to 12 hours or less (for example, 7 am to 6 pm or 9:30 am to 7:30 pm), you expand that recovery time, improving HRV and restoring autonomic balance. Twelve hours of eating a day is attainable. Try it, and, after a week, reduce the window by one hour until you reach eight hours of eating a day. This way of eating is called intermittent fasting or time-restricted eating.
Connect with nature several times a week. Over the past several hundred years, people have gradually shifted from working outside on farms and in fields toward a more sedentary life in offices and homes. Today, the average American spends more than 90% of his/her time indoors. Yet, study after study shows that more time spent in Mother Nature’s company leads to improvements in HRV. It also lowers stress levels (by flooding the body with calming, feel-good hormones) and improves immune function by increasing intake of phytoncides, aromatic plant compounds released by trees and other plants that trigger production of immune-supportive white blood cells.
Partner up. Intimacy promotes autonomic balance by making you feel cared for, safe and part of a community, all of which are known to tip autonomic balance in the right direction. Romantic or sexual intimacy works (anything from holding hands to having sex), as does platonic friendship, spending time with loved ones and even caring for a pet.
