Math & Sleep Cycles. How Much Should You Really Sleep?Oct 23, 2023
There is a lot of confusion out there about how much we should all be sleeping. The media and sleep experts say 7-9 hrs a night but is this actually true?
First it’s important to look at the facts. It is commonly agreed that healthy humans experience 4-6 sleep cycles a night (unless sleep is disturbed by things such as insomnia or sleep apnea)
A sleep cycle is composed of different sleep stages. Light sleep, deep sleep (which is broken down into 2 different stages) and REM.
In healthy humans, the average sleep cycle lasts 70-90 minutes.
Our Sleep Needs Vary
As you can see, the amount of sleep we all need naturally varies depending on factors such as genetic expression.
In other words, just as we are all different heights with different facial features, eye colors, hobbies, interests and shoe sizes, we all need different amounts of sleep!
Given these differences is it accurate or helpful to encourage everyone to aim for 8 hrs of sleep a night?
How to Logically Calculate Sleep Needs
Let’s do the math.. say someone is allowing plenty of time for sleep. They live a healthy lifestyle and wake up refreshed and ready to take on the day! This person’s body naturally cycles through the sleep stages every 70 minutes, which is the lower end of normal, and they wake after 4 cycles feeling refreshed (I actually know people like this).
When we sit down and calculate it out, this person is only sleeping 4.6 hrs a night but they are still going through a healthy number of sleep cycles and the length of these cycles is within normal range. This person is not tired and does not feel they are sleep deprived (until someone with no knowledge of their genetics, lifestyle or inner working tells them they are!)
So say theoretically, this person has been sleeping 4.6 hrs a night and feeling great for years. Then a book comes out. This book is a hot best seller, written by a supposed sleep expert and (because this person chooses to write in gross over generalizations without doing the math) the books whole message is that we all need to sleep at least 7 hrs a night or die a horrible early death!
How Trying Too Hard Can Lead to Less Sleep
Because this person (let’s just call her Jen) is very health conscious and has a grandmother with Alzheimers, she gets really freaked out (and who wouldn’t in her situation) given that the entire premise of the book is essentially that she is broken and something she has no control over is bad.
So, because she cares deeply about her health, Jen starts to really focus on sleep. She is now allocating large blocks of time (9 hrs or more) to lying in bed waiting for sleep to come. Because Jen naturally only sleeps 4.6-5hrs, she is left with 4 hrs or so to toss and turn and feel stressed about the fact that she is not sleeping, which leads to less sleep and more stress over time.
As we all know, sleep is a passive parasympathetic process so the more stressed or activated you are, the less you will sleep.
The Negative Effects of Sleep Efforts
Because she is not sleeping Jen no longer looks forward to the day. She is tired, headachy and wants to cry. Her every waking thought is now about sleep (or lack thereof) and she doesn’t feel rested enough to enjoy going to the gym, dinner with friends or anything else she used to love.
Her entire life is turning into 1 sleepless misery as restful sleep slips further and further away. Who can relate?
Given that science shows the average healthy sleep cycle lasts 70-90 minutes (90 is most common but NOT necessarily better) and most people experience 4-6 cycles a night, that sets the healthy human range for sleep at anything from 4.6 hrs all the way up to 9hrs. Add to this that multiple sleep lab studies AND large studies of tribal cultures (living very much as our ancestors did hundreds to thousands of years ago) show the average human sleep duration to be approximately 6-6.5 hrs a night, why are we all being pressured to sleep more?
Who is Sleep Advice For?
It is 1 thing to be young and fun and not care about sleep. If you are someone who commonly over packs their schedule, has a “I’ll sleep when I am dead” attitude and lives of energy drinks, then yes, you would likely benefit from re examining your lifestyle choices.
However, if you already place emphasis on your health and you feel rested after short amounts of sleep, then I really encourage you to take any generic sleep advice out there with a grain of salt.
Are Health Workers Really Informed on Sleep?
I personally have over 10 yrs of post high school education (mostly in health) and I can tell you, while we were fed a lot of facts and studies, not 1 professor ever sat down and did the sleep math with us that I just did with you. We were always told that less than 7 hrs was unhealthy, end of story.
This occurred in multiple programs at some very well-respected schools so I can almost guarantee you that if I was educated this way, so were the vast majority of health workers out there.
The result is many well educated people running around with good intentions, telling people something is wrong with them. Essentially parroting what we were taught without fully exploring the facts.
Science is always changing. Not too long ago (less than 20 yrs) when I was getting my nutrition education, balancing blood sugar levels was considered to be the holy grail of health (it still is in a way) but we were taught the best way to do this was through eating little and often and including fat or protein with everything. Now we are all told the liver does this naturally when we eat less so we should be intermittent fasting.
Who knows what science will say 20 yrs from now.
Science is Constantly Changing
The point is, even if the 7-9 hr myth was rooted in fact (which it’s not) science is always changing and theories evolve. Just because everyone says something, doesn’t make it true.
You are your own best expert. Just as we all have different heights, hair color and shoe sizes, we all need different amounts of sleep. No one else knows what it’s like to be you and (unless they studied you in a sleep clinic or took your saliva) they have no idea what your genetic structure looks like or the length of your sleep cycles.
So why, from their uniformed position, should they be the defining factor in how much you sleep?
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In the meantime, I would like to leave you with this important message. You are not broken! You are whole, perfect, and healthy exactly as you are, and you CAN sleep!
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