“If the stresses of a 24-hour news cycle, an email inbox that never turns off, and the on-going pandemic have you feeling a new level of exhaustion, take a deep breath – five seconds inhale, five seconds exhale - and know you’re not alone. I’m Sara Mednick, UCI cognitive scientist and author of The Power of the Downstate: Recharge Your Life Using Your Body's Own Restorative Systems. The pressures and information onslaught we experience in our modern world really work against our body’s natural rhythm, holding us in a constant upstate that has major consequences for our mental, physical and emotional well-being. My work focuses on providing science-backed solutions for engaging the body’s natural corrective downstate systems, and so I want to leave you with some actions we can take to balance our bodies, restore our reserves and take on the day.
But first: the science. And for that, I need to go back to where I started my research as a grad student.
I studied napping and its importance for memory formation, emotional processing, perception and all sorts of improvements in cognition. In the last fifteen years, we've developed a lot of technological advances and more sophisticated analytical techniques to understand what's going on in our brains and bodies during sleep. And what we've learned is that slow wave sleep - which happens during our deep sleep phase in the first few hours of the night - is the most important in terms of its restorative power. During slow wave sleep, the brain goes from a state of high activity with asynchronous firing of neurons to a much slower pace in which all neurons begin to fire as one. This synchronized firing allows for the transfer of information from short-term to long-term storage areas of the brain via large, coordinated brain waves. Each wave is one second long and has two sides - the upstate and the downstate. The upstate is where the whole brain is suddenly launched into action and all the neurons start communicating together. The downstate is the second half, and that's when the whole brain is silenced. We go through these upstate and downstate swings throughout the night, and they're what make sleep so powerful and so restorative. It's the period in which we experience clearance of all the toxins of the day, memory improvements, growth hormone increases, protein synthesis and so much more.
As a cognitive neuroscientist, I’m most interested in what sleep means for the brain. But as we all know, sleep doesn't just involve your brain. So, with my research team in the Sleep and Cognition Lab here at UCI, we started looking at the autonomic nervous system, measuring heart rate during sleep alongside EEG to assess what's happening in the rest of our body. And what we found was something really astonishing: the autonomic nervous system also has an upstate and downstate. There's a sympathetic system - which I call rev because it revs up your heart rate, respiration, sending energy where ever you need it most - and then the downstate, which is the parasympathetic or restore system that comes in directly after to calm everything down and repair all the wear and tear. The same is true about our body’s need for a recovery period after exercise, or a short fasting period after eating so that the body can restore its metabolic system. This rhythmic upstate/downstate system seems to be universal in terms of natural biological systems. So I wanted to really dive into how these rhythms work to understand if we can harness them to improve health. And it turns out we can.
I'm a sleep scientist by trade, so I know the restorative value it holds for our body and mind, but I think we put a little bit too much pressure on sleep to solve everything. We spend our whole day ramped up in rev and then ask sleep to do all the heavy lifting and that's just asking too much. So I started looking into ways we can work on restorative moments during the day, effectively ramping up and then bringing everything back to baseline every few hours so that the rev state isn't such a steep slope and you get yourself out of that relentless climb. There are lots of things that we can do to bring on restorative systems during the day, and the simplest step begins with your breath. Too often throughout the day, we're breathing in shallow quick breaths, or just stop breathing altogether - particularly when doing activities like email. It's an automatic stress response that we don't even notice, and so one of the best ways to really counter that and engage the restore system is by intentionally slowing your breathing down with deep slow breaths - five seconds inhale, five seconds exhale. Whether you're in a stressful situation or just sitting in your car, engaging in slow, deep breathing sends this very strong signal to your brain and body that you're safe, that you're in control. Breathing is the root of practices like meditation and yoga which add a cognitive and emotional layer that helps bring awareness to your body, breath and feelings in a way that's also very good for restorative processes during the day.
Another easy one is to get natural light first thing in the morning. It’s basically like a downbeat for the entire circadian rhythm. As soon as you wake, engage with the sun or if you can’t, get yourself a bright all spectrum light and spend 15 minutes near it while you're having your coffee or tea.
The next tip is timing. Properly time your eating and exercise, so that you have most of your upstate during daylight hours. This is the time when you have more glucose, more energy - all this stuff that runs your body. Your metabolism is at its height during the early day and then as the day wears on, insulin production goes down. Your heart rate is also supposed to naturally start going down by day’s end because your body is anticipating a big restore period. So, trying to time your eating to daylight hours helps your body process and then prepare for downstate time.
The same goes for exercise. Cardiovascular work should be done in the morning because it takes the whole day for your rev system to come down and for your restore system to take over, and since that happens during sleep, that allows for a really big burst of replenishing restoration of downstate.
Now what are some disruptors? Well, the modern world doesn't know or care about these rhythms. Between the hyper sensationalized 24-hour news cycle that constantly feeds us fear-based headlines, our email that never allows us to shut off, and then of course most recently the pandemic which added more stress and upheaved any and all routines and rhythms we might have had, it seems the modern world is doing everything to work against giving us equal opportunities in upstates and downstates. We spend far more time focused on and stuck in the former, and it's a mode that's very stressful on our bodies. The downstate is where we recover from stress and where we replenish our resources and get ready for the next upstate, whatever it is. If you have these prolonged periods where you're not giving yourself enough downstate to recover, you have chronic stress which leads to increased risk for diabetes, unhealthy weight, and chronic disease like hypertension as well as cognitive disorders like dementia and Alzheimer's. These are all stress related.
In my lab, we see a stark difference in downstate recovery between younger and older adults. Using EEG and EKG on sleep participants across the age spectrum, we see that the second younger adults go to sleep, they have this massive parasympathetic restore response with a coupling of the autonomic system, creating a highly restorative system-level response. When we put people who are 60 and older in the bed, we often see no change in system response from wake to sleep, meaning that older adults aren’t experiencing a strong – or any – downstate rhythm during sleep.
Why is this happening? Well, as we age, many of us just give up on some of our basic daily downstate activities. We don't get enough bright light in the morning or spend enough time outside in nature because we jump right into work. We spend more time sitting at a computer than at activities that harness our downstate - like yoga and meditation. We eat less fiber and colorful veggies, and more instant meals that are more comfort food than health food. All of these things make us more stressed, revving us into an upstate. So to counterbalance, we need to spend more time in the restorative downstate, which we just don't.
It’s important to recognize that recovery isn’t something you can bank. You can’t sleep more on the weekend to make up for lost z’s or eat healthier on Sunday to counter last minute weekday meals in the drive thru. You can’t be in a constant upstate throughout the week and expect to catch up on over a weekend of sleeping and eating better or exercising more. Toxins that build up from the wear and tear of life do so on a daily basis, and losing even one night of good sleep adds up. And we know the consequences: these toxins create plaques in your brain that put you more at risk for dementia and Alzheimer's in your 60s and 70s. So that’s why it’s even more important as we move into our 40s and 50s to take control where we can and do purposeful activities that engage our downstate and recovery system. Also remember that each activity you do throughout the day helps the other, so what you're eating affects exercise; exercise affects sleep; sleep affects what you're eating. And your autonomic nervous system is at the center of it all. These activities that engage our upstate/downstate rhythms are central to our well-being and health.
The good news: there's a lot of research to show that it's never too late to start. You can start exercising when you're in your 50s and slow the effects. You can get bright light in the morning - do whatever you can to enhance your restorative system now. Everything you change for the better today has benefits down the line.”