How much sleep do I need? (It’s less than you think) | Optimal Circadian Health

As a doctor with a strong interest in sleep medicine who sleeps 6 hours a night, I can tell you answering the question of “how much sleep do I need” is never as simple as “seven to nine hours” like the national sleep foundation says.

You see, sleep is complicated and quantity never equates to quality. You also need to consider what equates to restorative sleep and adequate sleep when asking “how much sleep?”

So, in this article, we’re going to dive into what makes AWESOME sleep happen, why you have sleep problems, and trouble sleeping. And, ultimately, yes, how many hours of sleep is “normal sleep” vs. “too little sleep” vs. “too much sleep”

Here’s to your sleep needs and you getting enough sleep! Let’s begin!

Sleep is a function

Understanding sleep is tricky, but we can simplify it. (Don’t worry, I know you may be sleep deprived).

Sleep is something your body does, just like eating.

So the question “how much should I eat?” depends on a multitude of factors.

What size are you? Did you work out a lot today? Are you trying to lose weight or gain weight?

So, the function of “eating” is to supply enough nutrients to support your body and whatever you’re trying to achieve.

The function of sleep is to reverse the cellular damage that has occurred throughout the day and to reset your neurons for the day ahead.

Hence, if you had a particularly stressful day, you might need more sleep at night.

That is, your sleep needs and sleep habits will depend on what happened that day and other demands on you.

So what exactly determines your sleep function and, thus, how much is enough sleep?

Your sleep depends on your underlying metabolic health

A good night’s sleep is directly correlated to your mitochondria (these are indeed the “powerhouse of the cell”).

Your mitochondria are essential for sleep. And, your mitochondria are the central point of your metabolic health.

Here’s a counterintuitive truth bomb: sleep is a highly energetic process and requires a lot of energy produced by your mitochondria to properly work.

And, while we’re here shattering your perception of sleep, the other important factoid is that your mitochondria produce melatonin.

Let’s revisit our “eating as a function” to put this into context.

If your body can’t digest nutrients very well, then you’ll then need to eat more to get the same amount of nutrients into your body. That is, an issue with the underlying function demands that you “eat more.”

For sleep, bad mitochondria decrease your ability to sleep. So, thus, you’d have to sleep more to get enough sleep (just like how you would have to eat more in the above analogy).

Generally, worse mitochondria means you have to sleep more to meet your sleep needs.

However, getting adequate sleep isn’t so simple…

Bad mitochondria Linked to Sleep Disorders

Unfortunately, the solution isn’t to just sleep more until your mitochondria improve because

poorly functioning mitochondria prevent you from sleeping longer.

Quite simply, mitochondrial disorder = sleep disorder.

Let’s break this down by sleep problem briefly here before diving into the numbers on sleep.

Too long to fall asleep

In sleep medicine, taking more than 20 minutes to fall asleep is called “sleep-onset insomnia” and is one of the most common sleep problems.

This happens because there isn’t enough melatonin to make you feel sleepy. This is partly because of poor mitochondria like we mentioned and also a suboptimal circadian rhythm.

Your circadian rhythm is a huge factor (dare I say “the” factor) for your sleep.

Briefly, your circadian rhythm is the timing of your metabolic processes such as releasing melatonin.

So, if your rhythm is off, then you won’t be releasing enough melatonin at the right time and it takes you too long to feel sleepy (like when you want to fall asleep).

Waking up throughout the night

Waking up at least once during the night and struggling to get back to sleep for at least 20-30 minutes is defined as “maintenance insomnia” in sleep medicine. These sleep patterns obviously disrupt sleep and decrease sleep quantity.

Essentially, waking up multiple times a night is due to an inability to maintain a stage of sleep or to transition between sleep stages which is directly tied to energy production during sleep.

And, the other factor is not enough melatonin production. In other words, there is not enough melatonin to stay asleep and this makes it hard to get enough sleep.

Waking up early unable to fall asleep

Waking up earlier than desired or planned (think 3/4 AM) and being unable to fall back asleep is known as “early morning insomnia” (and is one of the most annoying sleep patterns).

What happens here is that melatonin “runs out” and then cortisol spikes earlier to wake you up. This is a

Normally, melatonin suppresses cortisol function. But, if you have insufficient melatonin, then cortisol gets to “run wild” earlier than it should. Then, this wakes you up and prevents you from getting your sleep needs.

Waking up unrefreshed

When you wake up feeling like you haven’t slept, that’s “non-restorative sleep” and even called “sleep inertia.” This is very subtle, but one of the sleep disorders that’s the most important.

Seriously, this is a form of sleep deprivation that many people would classify as “my sleep is okay.”

If you’re not feeling refreshed when you wake up, then you’re having a problem!

What’s going on here is that there is too much adenosine leftover from the night. This adenosine came directly from the ATP (cellular energy) that your mitochondria made.

Yet, again, a poorly functioning mitochondria and circadian rhythm are at the bottom of your sleep issues.

Difficulty breathing at night

Another reason for poor sleep is sleep apnea.

As luck would have it, this is the primary sleep disorder in individuals with mitochondrial diseases.

The answer is to not just take melatonin!!!

Now, a simplistic summary would be “melatonin is low and we should fix that”

Which is true…

Supplementing melatonin in a pill can indeed help your sleep.

But also, the research is clear that the effect is marginal on average and doesn’t last beyond 6 months.

So, don’t take the short, simplistic route. I get that you need your sleep, but you need to dive into the deeper underlying issues so that long-term you have the benefit of great sleep and mitochondria.

Hours of sleep needed

Before we get to “how much sleep?” we need to discuss

These sleep issues are exactly why “seven to nine hours” doesn’t work across the board even if the national sleep foundation makes the broad recommendation.

You need to know about “sleep efficiency” which is the number of hours asleep divided by the hours in bed.

For instance, say you sleep 8 hours, but were in bed for 10 hours. That would be 8 divided by 10 which would be .80 or 80%

Ideally, you want your sleep efficiency to be above 90%.

Sleep efficiency is just like when we spend time with people in our life.

It’s not about the total hours, rather, it’s about the QUALITY of that time.

So, you must focus on quality first, then quantity!

(Don’t worry, we’ll talk about quantity once you have quality dialed in!)

What defines quality?

Sleep quality is defined as the PERCENTAGE of time spent in each stage of sleep.

For simplicity’s sake, we’ll focus on the most restorative stages of sleep here.

Quality – Why do you need deep sleep?

Healthy sleep has deep sleep (defined as N3 for my fellow sleep nerds) as about 25% of your total sleep duration.

Deep sleep is when your body repairs its “hardware” which corresponds to the more “physical” parts of your body (think of cell membranes, muscle cells, etc.).

When this stage suffers, many issues pop up such as:

1. Memory struggles and decreased brain function
2. Mood issues  and other mental health (irritability, depression, etc)
3. Weight gain
4. Heart disease and cardiovascular disease (including high blood pressure)
5. Low energy levels
6. Poor coordination and balance 
7. Micro-sleeps during the day
8. Reduced healing/immune system
9. Aging skin and wrinkles
10. Gut issues

The list of chronic diseases and mental and physical health issues goes on and on…

In other words, without deep sleep, you start to break down.

When you get sleep deprivation with insufficient sleep, your sleep cycles will have less of this stage.

Quality – Why do you need REM sleep?

Healthy sleep has REM sleep around 25% of your total sleep time.

REM sleep is when your body resets its “software” which is the electrical and chemical communications among all your cells.

The detriments of not getting enough REM sleep are similar to that of not getting enough deep sleep because without running the proper “software,” your “hardware” becomes inefficient and accumulates damage faster.

REM sleep is more important as noted when someone is sleep deprived and they drop right into this sleep cycle.

Having these above sleep cycles in order is the key to a good night’s sleep. 

So how are you supposed to know your quality of sleep? Do you need a sleep tracker?

Do you need a sleep tracker?

I wouldn’t say you need one. As it turns out, humans are semi-decent at subjectively rating their quality of sleep (see here and here) when dealing with sleep deprivation. (However, under very stressful circumstances, this relationship breaks down).

So, honestly, I wouldn’t say a sleep tracker is necessary. Just keep your focus on the most important factors.

Now, if you’re into sleep trackers already, I’d recommend my article on “Oura Ring vs Fitbit” here when you’re done reading.

Focus on Quality First

Think of sleep as growing a garden.

You want to grow broccoli, not just a bunch of weeds in the name of “growth”

When you expand the quantity (hours) of poor-quality sleep, then you continue to make your sleep worse!

This happens because as you spend more time in bed, you begin to create a negative behavior association between “bed” and actually sleeping.

(You know, when you’re laying there at night ruminating or anxious)

Remember how we mentioned “sleep efficiency”? When you try to prioritize sleep duration, you end up hurting your sleep efficiency and this continues to hurt your quality.

Hence, you want to limit your total time in bed within reason. I’m not advocating for sleep restriction here.

I’m advocating for smart sleep health by setting yourself up for success during the day for amazing quality at night!

Because, if you don’t then you don’t just accumulate sleep debt… you are actively piling up bad sleep on top of it.

Sleep Deprivation and sleep debt

Sleep deprivation is when you don’t get enough sleep and you accumulate “sleep debt”

And, I hate the term sleep debt because you can’t really pay it back.

Well, you can, but it takes you far longer to undo the damage of sleep deprivation by just “catching up” on sleep on the weekends or sneaking in daytime naps.

In fact, one night of sleep leads to an accumulation of “metabolic gunk” which is the same stuff that accumulates during dementia.

Hence, you need to prioritize quality before quantity. This will lead to temporary sleep deprivation, but if you’re using the right tools to improve your mitochondria then you get better sleep.

So how much sleep? What’s the best sleep duration?

And, now, for the question… how many hours of sleep?

First, if you’re getting less than seven hours and have none of the above issues and not having any daytime deficits, then you’re fine (and probably aren’t reading this article about 10 paragraphs ago). The same thing is you’re sleeping 8 hours or even 9 hours.

There is nothing magical that happens at least seven hours into sleep. Again, it’s about quality.

So instead of asking:

• Is it good to get 5 hours of sleep?
• Is 6 hours of sleep enough?
• Is 7 enough hours of sleep?
• Is 7 hours of sleep better than 8?
• What is the healthiest amount of sleep for adults?

You need to be asking:

• How long is it taking me to fall asleep?
• How many times am I waking up in the middle of the night?
• How long am I awake in the middle of the night?
• Am I waking up at a normal time?
• Am I waking up refreshed?

Focusing on these numbers and factors will pave the way for good sleep!

Then, you will end up with 5-6 good quality hours of sleep and then scale up to 7-9 hours from there!

Now you may ask, how much is too much sleep? If you’re sleeping more than 10 hours, you have inefficient sleep)

What are the best hours to sleep?

This is another common question.

Your sleep schedule is equally important because of your circadian rhythm.

Your circadian rhythm is the timing of processes… so you should time your sleep schedule too.

Which is why I get asked “is 10pm to 4am enough sleep?” all the time.

Here’s the thing, it depends on where your rhythm is at, what time of the year it is (more sleep in the winter and less in summer), and what you need.

How to start improving the quality of your sleep?

So, you’ll see a lot of advice from the sleep research society, your local sleep doctor, and from clinical sleep medicine.

Yes, you can have a bedtime routine, a sleep schedule, a sleep sanctuary, and a better sleep environment. And, even meditation for better mental health and relaxation to make falling asleep easier.

All of the above is good and dandy, but the core to falling asleep and optimizing your sleep wake cycle is optimized mitochondria and circadian rhythms which is why we created our free masterclass.

These are two huge factors that you need to understand in depth because when you know better, then you can do better.

We’ve seen a lot of people take the masterclass and make amazing progress in getting more sleep and good health.

Click the masterclass link at the top of our site or in the bottom right video panel there.

(Short note: Now, this entire article was for healthy adults. Older adults have different brain architecture and mitochondrial concerns. Older adults typically need fewer hours.)