Pam Strand (00:00):
Hello, my name is Pam Strand. I'm your podcast host and I would like to welcome you to the Longevity Gym. The Longevity Gym podcast is about learning to live longer, stronger, and better. Today's topic is sleep. Sleep is essential for longevity. High quality sleep helps us be healthy, helps us recover from the demands of our day and helps us become stronger both mentally and physically.

Our lives seem to just work better when we get a good night's sleep on a consistent basis. As someone once said to me, it's hard to be happy when you're sleep deprived. That's the truth, isn't it?

Sleep is a vast topic with many, many moving parts. Today I want to explore one part and that's what controls and regulates sleep. For I believe if we understand what happens within the body to cause sleep to occur, we're more able to adjust our lifestyles to better support our body's sleep process.
(01:02):
We'll start the conversation today defining what sleep is and what a good night's sleep looks like. Then I'll share the two main processes within the body that control and regulate sleep.

Let's get started.

What is sleep? That might sound like a little bit of a silly question. We all know what sleep is, right? We get some in some shape or form every night of our lives, but have you ever thought about what sleep is actually?

Sleep experts or doctors who practice sleep medicine may describe sleep as something like this. Sleep is a recurring physiological state where one is unconscious and disconnected from the surrounding environment and it is a state from which one can be aroused with stimuli.

(01:56):
In layman's terms, we might describe sleep like this.

Sleep is a period of regular rest where you are unconscious, your body recovers and your mind is refreshed.

Sleep is part of the sleep wake cycle that repeats in our body approximately every 24 hours. Sleep is also defined by stages and there are two types of stages, which I'm sure you know. There's REM and non-REM.

REM sleep is where there is rapid eye movement. During REM sleep, your mind is as active as when you are awake. I think that's pretty fascinating. Dreaming occurs in this stage and REM is where your mind is processing the day. REM sleep accounts for about 20 to 25% of your sleep time.

Then there is non REM sleep where there is no rapid eye movement. There are three main non REM stages. There's moving from wakefulness to light sleep, light sleep to deep sleep, and then deep sleep.
(03:09):
Brain activity slows down in non-REM sleep and it's where your body repairs bones, muscles and tissues. It's also where the immune system is strengthened. Non REM sleep accounts for 75% of our sleep time.

What does a good night's sleep look like?

We certainly know what it feels like, don't we? It's when we wake up refreshed and energized mentally and physically and we're ready for our day. And this is an absolute valid definition of a good night's sleep; and it's an important hallmark of high quality sleep over the long run.

The experts take it deeper so as to understand how to help people resolve sleep issues and if you have challenges with sleep, you may be interested in going deeper as well to understand what a good night's sleep is.

According to literature and to research and the experts, there are four main criteria for a good night's sleep.
(04:19):
The first one is seven to nine hours of sleep a night for the average adult.

The second criteria is that our sleep is uninterrupted and this accounts for things that are waking us up above and beyond the micro awakenings that naturally occur during the night and those micro awakenings occur about five to six times and they're so micro it's likely we don't even remember them.

The third main criteria is that the body moves through all stages of sleep. We'll see REM sleep as well as the three stages of non-REM sleep, and the fourth criteria is that there's adequate time in REM and deep sleep For mental and physical restoration.
(05:09):
Time in REM and deep sleep is very important. Sleep research suggests that 90 to 120 minutes of REM sleep is ideal. That's about 20 to 25% of your total sleep time. And that 60 to 100 minutes for deep sleep is ideal. That's 15 to 20% of your total sleep.

While science says that these are the four main criteria and the ideal targets for REM and deep sleep, it's important to remember that everybody's sleep profile is unique to them. So if you're waking up in the morning refreshed mentally and physically and ready to go for your day, you've probably had a very good night's sleep.

The other thing that's important
(05:56):
to know about sleep is that we can't control how much of each stage our bodies get each night. So we can't say, I'm going to go to bed tonight and I'm going to get 90 minutes of REM and 75 minutes of deep sleep. It just doesn't work that way.

Nor can we control how long we sleep.

But we can certainly strongly influence whether we get a good night's sleep by doing what we can to prepare our bodies and minds for consistent high quality sleep.

And that's where our next topic in this podcast comes into play.

We're going to dig deeper in understanding how our sleep is regulated. For if we understand tha,t we can go a long way in tailoring our lifestyle behaviors and habits in a way that support the sleep process within our bodies.

Sleep is a biological state that's regulated mainly by two processes, our sleep drive and our body's circadian rhythms. Let's look at our sleep drive first.
(07:05):
Sleep drive is the physiological need for sleep. It's a process of homeostasis that our physiology governs in a balanced manner. In other words, the body is naturally predisposed for the need for sleep.

In one of my courses, I even learned that it's biologically impossible for the body not to sleep.

The need for sleep builds as we are awake. The longer we are awake, the more pressure within the body to go to sleep. A high sleep drive helps you fall asleep quickly when you go to bed and during the night, there are physiological changes that occur that lessen the sleep drive so that you eventually wake up in the morning.

Sleep drive is a key part of regulating our sleep wake cycle. There's not yet a great deal known about what actually controls the sleep drive, but over the past few years, experts are focusing more on a biochemical in the body called adenosine.
(08:09):
Adenosine helps regulate sleep drive, and it's also part of the process within the body that creates energy for our muscles to move and our bodies to function. This chemical builds up in our brains during the day, increasing our sleep drive into the evening. And then it clears while we are asleep.

Our lifestyle habits significantly influence the production and regulation of this chemical, adenosine. Lifestyle habits that can help build the production of this biochemical during the day are these:
Getting regular exercise each day
Having a consistent sleep schedule, which means getting to bed and waking up at the same times each day,
Eating a balanced,
(08:54):
Nutritious diet that includes all the macronutrients, the carbohydrates, proteins and healthy fats, as well as making sure we're getting adequate amounts of fruits and vegetables.
And then the fourth main lifestyle habit that helps build the production of this biochemical is keeping our sleep environment dark, quiet and cool.

There are of course lifestyle habits that can disrupt our sleep drive and those include these:
A lack of regular exercise and movement throughout the day.
Stress, especially chronic stress,
Caffeine can disrupt the sleep drive because it actually does interfere with the function of the adenosine within our brains.
Alcohol disrupts sleep drive. Alcohol may make it easier to fall asleep, but when alcohol is processed in our body, because it's processed as sugar, it's a stimulant in our systems.
And the fifth main lifestyle habit or behavior that can disrupt our sleep drive is smoking, which stimulates the nervous system and makes it harder to fall asleep and stay asleep.
(10:07):
It probably sounds like there's nothing new on this list. Our health routinely comes down to these behaviors and habits that I've listed. Maybe knowing that these aren't just healthy things to do can bring a new urgency to making sure you incorporate them into your lifestyle if you're not already doing so.

Each of these lifestyle factors impacts specifically the physiology in our body that regulates and controls sleep. In fact, your body is counting on them in order to keep its physiology on target and in balance.

The same is true for our circadian rhythms, so let's look at that next.

Our circadian rhythms are physical, mental and behavioral changes that we experience within our body over a 24 hour cycle, virtually every tissue and organ has its own circadian rhythms. Our circadian rhythms rely on internal signals and external cues.

The internal signals are things like hormones, neurotransmitters, and other biochemicals.
(11:15):
The external cues come from the external environment, at least the environment that's external to the body, so this includes:
Light and dark cycles,
Temperature changes that occur throughout the day, and
Lifestyle factors such as whether you're getting physical activity, how well you're resting, the social interactions you have, the food and the timing of when we eat, how we manage our stress and how consistent our sleep schedule is.

Something that I find very fascinating and actually very useful to know is that our circadian rhythms aren't exactly 24 hours, so they need these external cues to stay on schedule. I think that's pretty fascinating. These cues are like timekeepers, without them our biology would run adrift. You likely feel this in your own body if you don't exercise regularly, maybe you're eating at different times than normal or eating a whole bunch of different foods or you don't get to bed and wake up at the same time.
(12:21):
When those things happen, it does feel like things are kind of off. And it's true because our physiology and our biology is off.

Again, lifestyle factors on the list are repetitive to what we are told are healthy things to do, and again, maybe knowing that these factors are actually nudging your body to stay on schedule adds a little more motivation to stay consistent in practicing them.

With that context, let's dig deeper into the main circadian rhythms that control and regulate our sleep wake cycle, and then we can also consider how lifestyle affects whether they stay on schedule or not. The main rhythms controlling our sleep are one the master clock that resides in our brain, which synchronizes all of our other internal clocks. The other main rhythm is melatonin. Then we have serotonin, and finally we have cortisol.

So let's look at each of these first, the master clock.
(13:29):
The master clock in our brain resides in the hypothalamus, which sits at the base of our brainstem. This master clock is called the Suprachiasmatic Nucleus or SCN for short. It uses or the SCN uses light signals coming in through the eyes to synchronize all of our body's internal clocks. This is why getting sunlight exposure first thing in the morning is important even if it's cloudy outside or even if you can't get outside at least sitting by a window to get the first bits of sunlight coming in through your eyes.

Having your eyes exposed to sunlight tells the body the morning has started and sets the clocks accordingly. Exposure to light during the day and into the evening is also helpful in keeping the master clock in sync and informed and on schedule. The second main rhythm is the excretion of melatonin, and melatonin is the hormone that makes us sleepy and helps us go to sleep. Melatonin goes to work when it's dark out. That's a key point. Its excretion starts around nine to 10:00 PM and peaks in the middle of the night and then it drops off in the morning, which allows us to wake up. As I mentioned, melatonin goes to work when it's
(14:50):
Dark, so being outside as the sun sets or when it's dark outside is a helpful thing to do to support the excretion of this hormone. Also helpful is dimming the lights in the evening or turning off any lights that you don't need in the evening. All of that supports how melatonin works. Some people even use warm or amber colored lights for the lights that are left on at night. I've heard also some people using infrared lights in their bedroom.

Melatonin doesn't work well when we're exposed to bright lights. This is why limiting screen time on electronic devices is important in the evening and nighttime. General guidelines are to turn devices off at least two hours before going to bed so as not to disrupt the functioning of melatonin. Here's an interesting point. Melatonin also needs the presence of serotonin. Serotonin is a precursor to melatonin for serotonin turns into melatonin in the brain.
(15:55):
Let me say that again because there's a lot of “tonin” going on here. Melatonin also needs the presence of serotonin. You can consider serotonin as a precursor or a prerequisite for melatonin because in the brain, serotonin turns into melatonin.

Let's look at serotonin. Serotonin is a neurotransmitter or a chemical signal in the body that promotes wakefulness and it also helps the master clock, the SCN, to process the light signals that come in through our eyes. It also inhibits or turns off REM sleep.

Serotonin peaks in the late morning to early afternoon and we want enough of serotonin in our bodies as we approach the evening so melatonin can begin its work.

Here are the lifestyle factors that we can use to support and increase its production. Regular physical activity, especially aerobic exercise, exposure to daylight, so that means sunlight first thing in the morning and at times throughout the day interacting with people. Yes, our social interactions really do support serotonin, making sure we have a healthy diet, especially one that's rich in tryptophan and finally doing what we can to have a healthy gut. For it is estimated that 90% of serotonin is produced in the large intestine.

and the fourth circadian rhythm that has a significant impact on our sleep wake cycle is cortisol. Simply put, cortisol is a hormone that activates energy within the body. It helps us be alert. Its levels rise in the morning and peak around six to 8:00 AM.
(17:49):
It's what gets our energy going and gets us up and out of bed and ready for the day's activities. It then gradually decreases throughout the day and hits its lowest levels in the evening and first part of night.

There are naturally occurring levels of cortisol in our bodies over a 24 hour cycle. As you can imagine, the amount of cortisol is also dependent on how much activation our systems get during the day. The body's stress response triggers a release of cortisol. And stress, if you remember from some previous episodes, comes in many forms and it's not just what you worry about. Stress is any demand put on our systems that disrupts the body's homeostasis or balanced state, so that can be a lot of things from poor nutrition to relentless schedule or demanding deadlines, intense exercise, illness, injury, irregular sleep schedules, traveling to different time zones. All of these things are examples of potential stress on our systems and that can raise our cortisol levels.
(19:04):
The key with cortisol is not to have too much extra cortisol when heading into the late afternoon and evening and also realizing that cortisol sometimes needs help clearing from the body. If we have too much extra or too much cortisol in our bodies when we're heading into the evenings, it's just going to take a little bit longer for our bodies to downshift and to move into a relaxed state that promotes sleep

Too much cortisol will make it difficult to get to sleep and stay asleep.

As we head into the evening, we want to be thinking about rest and relaxation, doing those things that we can do to promote a downshift in our body and clear cortisol levels. Examples of lifestyle behaviors or habits that can promote this downshift include closing out the demanding parts of your day in late afternoon, eating a healthy well-balanced meal in the evening (we want to be able to keep blood sugar levels stable), doing or performing moderate to light aerobic exercise in the evening like a easy stroll after dinner, light stretching or restorative yoga or other type of mindful movement, light reading, listening to calming music, practicing meditation and mindfulness and slow breathing.
(20:33):
Being around people who are supportive and loving with you. Being with people in the evening actually downregulates our nervous system.

Another thing that many experts focus
(20:47):
Is to have us focus on gratitude and positive thoughts in the evening, spending a few moments maybe recalling what went well during the day. This really helps soothe the mind and relax and downshift the mind. And also working to reduce chronic levels of stress will help promote downshifting the body in the evening.

There are many habits and routines that can disrupt the cortisol levels and keep them higher than normal, and those things are consuming caffeine later in the day. Alcohol and eating foods in the evening that are high in processed sugars that spikes our sugar levels during the night. Scrolling on social media and the internet late in the day - that moving from topic to topic actually activates the mind. Being on electronic devices can also activate the mind. It puts it on alert so it has difficulty downshifting. Working on intense projects. Staying up late to watch high intensity movies, even high intensity exercise late in the day or evening can increase cortisol levels that disrupt this downshifting of the body and its systems as it prepares for sleep.
(22:08):
If you feel like better sleep would improve your health and your life, it's an important issue to address. Reoccurring and significant issues with sleep should be evaluated with the help and guidance of your doctor. You want to rule out the potential of any medical issues and get the support if an issue needs medical intervention like sleep apnea.

As I said at the onset of this episode, the more we know about the sleep wake cycle, the better we can equip ourselves with habits and practices that keep this cycle on track so we can enjoy high quality sleep. The more we can use our lifestyle choices to make the rhythm of sleep wake work like clockwork, pun slightly intended, the more likely we will have healthy sleep that supports our desire to live longer, stronger, and better.
(23:02):
I hope you found something useful in this episode. As always, if you have any questions or comments, please email me. My email is pam@strandfitnessonline.com. It's also listed in the show notes below, and if you're not already on my newsletter, I invite you to sign up. I have included a link in the show notes below. I email newsletters about every two weeks letting you know about recent podcast episodes, and I also share information and tips for living a longer, stronger, better life.

So that's a wrap. See you next time