Post #33: Mastering the Art of Sleep: Snoozing Like a Pro

Today’s topic (#33) is inspired by my sister who truly values her sleep the way I value a trip to Ghirardelli for the Golden Gate Banana Split. She waxes eloquent about her sleep score being in the high seventies for an entire week with a great sense of pride and is equally concerned when she hasn’t slept well. Good quality sleep was at a premium for me for most of my life but my lifestyle changes over the last couple of years have made a massive difference to my sleep quality. Various reports show that 30% of Americans suffer from insomnia while 61% of Indians get less than 6 hours of quality sleep. Sleep shortage is a global problem and one that seems to be getting worse over time.

Let’s get into the basics of sleep; a topic that I could have probably covered in one word if I had to describe it ten years ago: boring. However, the more I delved into it over the last decade, the more I was fascinated by how sophisticated a mechanism our body has developed, in order to allow us to function at our best every single day.

Introduction to the Sleep Stages: The objective of sleep is to maintain both good physical and mental health. At a high level, sleep can be thought of as having four key stages: Awake, Light, Deep and REM, with some of these stages being further divided into substages. Each cycle of sleep typically consists of our body going through all the stages, with every cycle lasting about 90 minutes. In one sleep cycle, we typically transition from awake to light to deep to light to REM (as you can see very nicely in the figure above for the first 90 minutes of my sleep); however it isn’t always so clear cut with a few cycles not having one or more of the stages (as you can see in the image in the second half of my sleep). An individual usually gets through 4 to 5 such cycles during sleep. I will go through what happens to our body in each stage of sleep as well as describe what the benefits of that stage are.?

Awake Period: You may wonder why this is considered a stage of the sleep cycle because it isn’t intuitive. While awake time is the time spent in bed before falling asleep and after waking up, it is also the time spent between each of the 4 - 5 cycles of sleep. Every night, in addition to waking up to use the bathroom, we also wake up for very small periods of time, which we may not even remember. These awake times are completely normal as long as you wake up feeling rested in the mornings. If you don’t feel rested, check for sleep apnea or other conditions in your sleep environment (room temperature, darkness, etc.) that may be causing you to wake up.

Light Sleep: The name “Light Sleep” is misleading because it’s a key stage of sleep that delivers benefits to our brain and body, including consolidating memories, enhancing our motor skills and boosting creativity, and we spend about 50% to 60% of our total sleep in this stage. Light Sleep consists of two sub-stages; during the first substage, which lasts for a few minutes, our muscles begin to relax, our body temperature begins to drop, our heart rate decreases, and if someone tries to wake us up, we can wake up relatively easily. In fact, in this substage, sometimes we think we are still awake even though we aren’t; that’s how light this sleep is. During the second substage, in addition to everything slowing down as in the first substage, our brain emits rhythmic brain wave patterns known as sleep spindles and K-complexes (simply put, they are mechanisms employed by the brain to help keep us asleep by blocking out external noises and disturbance and help with memory consolidation).

Deep Sleep: This is the most rejuvenating stage of sleep, where our bodies get busy repairing and restoring the various systems within, from promoting muscle growth and repair to improving insulin sensitivity to reducing cortisol (our stress hormone) levels, to flushing the brain of all the gathered waste products. During this stage, which lasts about 10% to 25% of our total sleep (there are significant differences between genders and age groups), our blood pressure drops, our heart rate and breathing are at their lowest, and our muscles are relaxed. This is the stage when it is hardest to wake up because of how much our body has shut down for maintenance. We end up spending more time in deep sleep during the first half of our total sleep and less so in the second half.

REM Sleep: REM or Rapid Eye Movement gets its name because our eyes move rapidly behind our closed eyelids. In fact, when I was a kid I used to think my cousins were pretending to be asleep when I saw this. This is the stage where primarily our brain goes into maintenance mode, connecting and reorganizing information, and does this by effectively pruning and trimming the synapses in our brains to consolidate our learnings through the day. Additionally, REM sleep plays a role in managing emotions by reducing activity in the amygdala, the brain's center for anxiety, stress, and fear. This is the reason we often are less stressed in the morning after a good night’s sleep than we were at the end of the previous day. During this stage, which lasts about 15% to 25% of our total sleep time, our heart rate, breathing and brainwave activity speed up and are more similar to when we are awake. This is the stage when we have most of our dreams and a fun fact is that during REM sleep our brain temporarily paralyzes most muscles, preventing us from physically acting out our dreams. While the brain is highly active during REM sleep causing vivid dreams, it suppresses motor signals to our muscles, allowing only essential functions like breathing and eye movements to continue. This muscle inhibition is a protective mechanism to ensure we remain still and avoid injury while dreaming.

Other Key Sleep Quality Metrics: In addition to the four stages of sleep, there are two other metrics that are quite insightful in gauging the quality of one’s sleep: the heart rate when sleeping and the heart rate variability through the night. I have written about both these metrics in significant detail in past posts so I won’t get into explaining what they are. However, it is useful to understand how a good night’s sleep should look in terms of these metrics.

Sleeping Heart Rate (SHR): As the name suggests, it is our heart rate through the period of sleep. As always, the lower the better in most cases but what is more instructive is the shape of the heart rate curve through the night. The shape provides very useful clues on the root cause of any poor sleep issues. Let’s start with what a good SHR curve should look like. It should look like a hammock; higher at the start and the end of our sleep time and lowest in the middle of our sleep. This suggests that our body has had the opportunity to be fully rested and when we are about to wake up, all the different internal systems are coming online again. Conversely, the two SHR curve shapes that are indicators of poor sleep quality are one where the heart rate takes a long time to drop to its lowest levels i.e. the body didn’t get enough time to truly feel rested, and the one where the SHR stays elevated throughout the night. The former is an indicator that our metabolism has been working hard through the night, either because we had a late meal or a very carb heavy meal or worked out pretty late in the evening or had a “significant” amount of alcohol late at night. The latter is an indicator of over-exhaustion.

Heart Rate Variability (HRV): While a higher HRV value is associated with better sleep, it is useful to note the shape of the HRV curve over the duration of the sleep. A Fitbit provides only a single average HRV number for the total sleep but wearables like the Apple Watch and the Oura Ring do provide the HRV values through the entire sleep duration. During deep sleep and certain parts of light sleep, HRV values tend to be higher because the body is more relaxed, while during REM it tends to go lower. Having said that, the ideal HRV curve is one that either stays high through the night or goes up over the course of the sleep duration.

Using Wearables to Analyze Sleep: Each of these stages of sleep, as well as SHR and HRV, are tracked by most of the popular wearables, such as the Fitbit, Apple Watch, Oura Ring, Whoop Band, etc. While the different wearables have different levels of accuracy when detecting the different stages of sleep or measuring SHR and HRV, the Oura Ring and Apple Watch tend to come closest to the gold standard when it comes to sleep markers. On this topic, I should mention the following point because I hear this often: Some people find it annoying or uncomfortable wearing one of these devices at night, and instead use how they feel when they wake up in the mornings as the best measure of their sleep quality. That is no doubt the ultimate metric. I find that when we tend to struggle with our sleep and want to diagnose what may be contributing to it, the wearable data often provides some very useful information.

Analyzing my Sleep: The figure at the top of this article is my sleep data for one night. As you can see above, most of my deep sleep happened in the first half of the night while my REM sleep happened in the second half. My Light Sleep for that night occupied 59% of the total sleep time, while my REM and Deep Sleep accounted for 21% and 20% respectively of the total time. You can also see many small and one slightly larger awake period in the top part of my Fitbit data image. You will notice that my SHR curve looks like an asymmetric hammock, indicating that I would have benefitted from a slightly longer sleep duration because it would provide that extra time to let my SHR bottom out nicely. My HRV curve was good because it stayed reasonably elevated throughout the night. All in all, based on these metrics, I would rate my sleep a solid 7.5 out of 10, with a good amount of time spent in the various sleep stages and a reasonably good HRV. However, I would have rated it a 9 on 10 had my 5 hour 4 minute total sleep been closer to my 6 hour average, because I would have felt more rejuvenated. In addition to rating my sleep based on my sleep metrics from the wearable, I tend to give my sleep a score based purely on how I feel when I wake up in the morning and before I look at my wearable metrics. On this day, I had given my sleep a score of 7 (on 10). I have found that for the most part, how I feel in the mornings and what my sleep markers suggest, seem to line up very nicely. On days that I didn’t think I slept well, I figure out which of the six markers of sleep were off and then diagnose what could have caused the issue.??

Converting my Learnings to Best Sleep Practices: I have covered this topic in past posts but the learnings keep evolving so here are my updated set of 10 habits that I (try to) follow on most nights, in order to give me the best shot at a restful night’s sleep. I can’t follow all of them every night, but the more I can remember to take care of, the better my sleep.

Early Dinner. Light Dinner: The last meal of the day needs to preferably happen 3 hours before bedtime and should be the lightest meal of the day. Any food that contributes calories should be counted as the last meal of the day because it puts a strain on our digestive system. Getting as much of the digestion process out of the way before we get into bed is important. Research from Columbia University has shown that diets low in fiber and high in saturated fat content and sugar tend to cause poor quality sleep, so a light dinner with more sources of fiber, foods with more unsaturated fat (seeds, nuts, fish, avocado, etc.) and low sugar intake will help. When this is followed, it has shown to positively affect our Deep Sleep, SHR and HRV values.

Walk a Mile … while Listening to Music or Learning Something New: I tend to walk for 20 minutes after every major meal, which ends up being almost exactly one mile, but any amount of walk is beneficial due to its impact on managing one’s blood sugar levels. Research from the University of Wisconsin has shown that if you do something relaxing, like listening to soothing music or if you learn something new (like a new language on Duolingo or a new topic through a podcast), it helps with improving your Deep Sleep. Those are just some examples of things one can do while walking (I tend to listen to podcasts).

Minimize Alcohol and Avoid Coffee at Night: I should be saying avoid alcohol completely, because as my friend Dennis found, going off alcohol for about 2 months improved his HRV and his sleep quality in very meaningful ways. However, I also know that isn’t necessarily a practical answer just like asking me to give up my Ghirardelli Golden Gate Banana Split (I have now mentioned this twice in one post which means I need to scratch this itch). Both alcohol and coffee consumption too close to bedtime will impact our REM sleep negatively. They will also impact the amount of time we spend in the awake state during the total sleep cycle. Alcohol may help you fall asleep sooner while coffee will not, but both also impact Deep Sleep time negatively. Bottom line is to have them as much before bedtime as practically possible.

Exercise: Getting cardio or strength training during the day has been shown to positively impact Deep Sleep. It is okay to exercise at most times of the day that work for you but it is preferable to avoid intense exercise for a couple of hours before bedtime because the adrenaline rush makes it hard to fall asleep and the metabolism keeps going well after the activity is over. I noticed that if I exercised late, my Deep Sleep would still be positively impacted but my REM sleep was worse.

Be Consistent with Bedtime: While total sleep time is important, what studies have shown conclusively is that trying to maintain our bedtimes to within a one-hour window every day is equally critical. When we move around our sleep windows, our bodies tend to get confused, leading to us not getting enough Deep Sleep because that occurs in the first part of the sleep cycle.

Manage Light Exposure: Research from Groningen University as well as from Professor Matthew Walker at Berkeley has found that later first-light exposure (in the mornings) and later light exposure at night both negatively influenced REM sleep patterns. So walk outside in the mornings to get natural light exposure and avoid screens for as much time as practically possible before going to bed. Avoiding screen time before bedtime is the one I have historically found the hardest to manage. I have switched to blue light blocking glasses but I really should use the last 30 minutes before bedtime to do something more relaxing than answering WhatsApp messages.

Maintain a Cold Environment: As discussed previously, our body temperature drops during Deep Sleep (first half of the night) and increases during REM sleep (mostly during the second half of the night). Therefore, there is a higher chance of waking up hot and sweaty during the second half when we are in the REM sleep stage. To avoid this, keep the room as cool as is comfortable (60 to 67 degrees Fahrenheit or 15 to 20 degrees Celsius). Take a hot water shower before bed because it helps to raise our body temperature slightly, and when you step out of the shower into cooler air, our body experiences a drop in core temperature. This cooling effect mimics the body's natural temperature drop that happens before sleep, signaling that it’s time to rest. In addition, a hot shower can relax our muscles and reduce tension, promoting a feeling of calm and helping to prepare our mind and body for sleep. Avoid taking a cold water shower before bed because it leads to a feeling of alertness, which isn’t what we want before bedtime. Go light on the night time clothing and choose sheets that are cool and comfortable.

Use a Massager before Bedtime: With the advent of hand held massagers like the Theragun and others, I have found that using it even for 5 minutes before bedtime, leads to better quality sleep. This is because a massager helps with muscle relaxation (which our body needs to go through during the Light Sleep stage and this helps get the body ready), improved blood circulation (which also promotes the body relaxing), and overall stress reduction by lowering our cortisol levels.

Ensure Good Magnesium Levels: The neurotransmitter GABA regulates REM sleep by acting like a "brake" to prevent over-excitement of neurons, which can help reduce anxiety, promote relaxation, and improve sleep. GABA activity is determined by a number of factors, including our Magnesium and Zinc levels, our stress, amount of exercise and the quality of the microbiome in our gut. Magnesium levels can be determined through a blood test and, if low, is a relatively safe supplement to take.

Avoid Benzodiazepines: Sometimes when we have trouble falling asleep, we take sleep medication (at least I used to do this a while back). Be very careful of what medication you take. The sleep medication that is sometimes prescribed under various brand names, such as Valium, Xanax, Restoril, Klonopin, etc. all are benzodiazepine based. Recent studies by Prof. Walker and others have shown that both the short term and long term risks are not worth the benefits they provide. They increase the risk of cardiovascular events significantly and also increase the risk of falls and accidents in older adults. Having said that, on the few occasions (3 to 4 times a year) I do need help with sleep, I take Advil PM which uses diphenhydramine, a first generation antihistamine, that is responsible for its sedative effects. It is very important to point out that this is NOT a good long or even mid term solution because the side effects include causing next-day drowsiness, impairing memory and cognitive function and over time our bodies develop a tolerance to the diphenhydramine, leading to resistance to Advil. Please speak to a doctor before doing this.

So, that’s what I have on this topic. I hope it didn’t put you to sleep unless you were listening to this last thing in the night, in which case I hope it did put you to sleep. I am sure many of you have some of your own best practices for a good night’s sleep. I would love to hear about them in the comments section. Until next time …

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