Sleep Optimisation and Deep Sleep Biology: The Longevity Lever Most People Still Underestimate

If there’s one thing I’ve learned after years of working with high-functioning people who genuinely care about their health, it’s this:

Most people think they sleep well.

But very few people actually do.

And even fewer understand what sleep is really doing behind the scenes.

Sleep is not just “rest”. It’s not a passive shutdown. It’s one of the most active biological repair states your body ever enters. It’s where you clean up neurological waste, stabilise mood, regulate inflammation, consolidate memory, rebalance hormones, and reset the nervous system.

If you’re healthy and you’re already doing the basics, eating reasonably well, moving your body, taking supplements, tracking biomarkers, then sleep becomes one of the highest-return optimisation levers you’ve got.

Not because it’s trendy. Because it’s foundational.

And when sleep is off, everything else becomes harder.

In this post, I want to unpack four topics that matter hugely for healthy people wanting to optimise longevity:

• Deep sleep vs REM and cognitive longevity

• Glymphatic clearance and dementia risk

• Sleep fragmentation and inflammation

• Genetics of sleep timing (chronotype)

And I’ll also show you how we use Life X DNA®’s Ultimate Pro Kit to uncover the hidden genetic and biochemical factors that can make sleep either effortless or a constant uphill battle.

Let’s get into it.

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1) Deep Sleep vs REM: Why Both Matter, But Deep Sleep Is the Heavy Hitter

Most people have heard of REM sleep. It’s the famous “dream sleep”. It’s also what your smartwatch loves to highlight, because it looks sexy on a graph.

But in my opinion, the sleep stage that deserves far more respect is deep sleep, also known as slow-wave sleep.

Deep sleep is the closest thing your body has to a nightly “repair mode”.

It’s when:

• Growth hormone is released

• Muscle repair accelerates

• Immune function is reinforced

• The brain begins clearing metabolic waste

• The nervous system downshifts into parasympathetic dominance

Deep sleep is also the stage most strongly linked with physical recovery and long-term resilience.

REM, on the other hand, is more closely linked with:

• emotional processing

• memory integration

• creativity

• psychological stability

So which is more important?

The truth is you need both. But here’s the key difference:

Deep sleep is the stage most likely to decline as you age.

And once deep sleep declines, the brain becomes more vulnerable over time. Not overnight, but slowly. That’s where cognitive longevity starts to become a real conversation.

Healthy people often ask me, “How much deep sleep should I get?”

There’s no perfect number. But as a general optimisation target, many adults do well aiming for:

• Deep sleep: ~15 to 25% of total sleep

• REM sleep: ~20 to 25% of total sleep

Now, wearables are not perfect. They estimate sleep stages, they don’t truly measure them like an EEG. But they are still useful for trend tracking.

What I care about is not a single night.

I care about patterns.

If your deep sleep is consistently low, and you’re waking up unrefreshed, mentally foggy, or relying heavily on caffeine to function, then we’ve got something worth fixing.

And this is one of the reasons I’m such a fan of Life X DNA®’s Ultimate Pro Kit.

Because for many people, low deep sleep is not just “stress” or “bad habits”. It can be driven by things like:

• neurotransmitter imbalance

• methylation inefficiency

• poor detoxification pathways

• histamine intolerance tendencies

• cortisol dysregulation

• micronutrient cofactor needs

And those are things we can actually identify and correct intelligently.

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2) Glymphatic Clearance: Your Brain’s Nightly “Waste Removal System”

This is one of my favourite sleep topics because it’s both fascinating and deeply relevant to longevity.

Your brain has a cleanup system called the glymphatic system.

It’s basically a waste removal network that clears out metabolic by-products, including proteins like beta-amyloid, which are strongly associated with neurodegenerative disease.

And here’s the kicker:

The glymphatic system is most active during deep sleep.

Not during meditation. Not during relaxation. Not during a nap while scrolling.

Deep sleep.

This is one of the reasons deep sleep is increasingly being discussed in the context of Alzheimer’s and dementia risk.

To be clear, I’m not saying one bad week of sleep gives you dementia. That’s not how biology works.

But what we do see is that:

• chronic poor sleep

• chronic sleep fragmentation

• reduced deep sleep over years

…is associated with increased neuroinflammation and increased risk of cognitive decline.

If you’re a healthy person trying to optimise longevity, you should care about this.

Because brain longevity is not just about memory. It’s about personality, independence, mood stability, and your ability to function at a high level into older age.

Deep sleep is not optional if that’s your goal.

This is also where genetic insight becomes powerful.

With Life X DNA®, we look at thousands of genes and millions of variants that influence things like:

• oxidative stress

• inflammation regulation

• methylation efficiency

• detoxification

• neurotransmitter pathways

• sleep-wake signalling

So instead of guessing why someone’s brain feels “wired but tired”, we can often see the deeper pattern.

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3) Sleep Fragmentation: The Quiet Destroyer of Recovery

Now let’s talk about the real villain.

Not sleep duration.

Not sleep timing.

Sleep fragmentation.

This is when you technically get 7 to 8 hours “in bed”, but your sleep is broken into chunks. You wake up briefly, sometimes without remembering it, and your sleep architecture becomes unstable.

From a recovery standpoint, fragmented sleep is like trying to charge your phone with a cable that keeps disconnecting.

You might still get some charge, but you’ll never reach 100%.

And the consequences are bigger than people realise.

Sleep fragmentation drives inflammation

When your sleep is fragmented, your body interprets it as a stress signal. This increases:

• cortisol dysregulation

• sympathetic nervous system activity

• inflammatory markers

• insulin resistance

• appetite dysregulation

In other words, your body becomes more reactive.

This is one of the reasons fragmented sleepers often report:

• more anxiety

• more pain sensitivity

• more fatigue

• more cravings

• more difficulty building muscle

• more stubborn body fat

Even if they’re doing “everything right”.

Fragmentation also reduces the quality of deep sleep and REM sleep. So you get the double hit:

• less repair

• less brain processing

The most common causes I see

In healthy people, the most common drivers of fragmentation are:

• Alcohol (even small amounts)

• Late-night eating

• Blood sugar instability

• Stress and nervous system hyperarousal

• Sleep apnoea (yes, even in fit people)

• Histamine issues (very common and under-recognised)

• Too much light exposure at night

• Too much heat in the bedroom

And one of the biggest ones:

A mismatch between your chronotype and your lifestyle.

Which brings us to the genetics side.

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4) Chronotype Genetics: You Can’t Biohack Your Way Out of Your Biology

Chronotype is your genetically influenced sleep timing preference.

Some people are naturally early birds. Others are night owls. Most people are somewhere in the middle.

Chronotype isn’t just a personality trait. It’s deeply biological.

It affects:

• melatonin release timing

• cortisol rhythm

• core body temperature cycles

• hunger hormones

• cognitive performance windows

And importantly:

Chronotype affects how restorative your sleep is.

Because if you are a true night owl, and you’re forcing yourself into a 9 pm bedtime every night, you might fall asleep, but your sleep architecture can be compromised.

Likewise, if you’re an early chronotype, and you’re staying up late because “you should be able to”, you’re essentially forcing yourself into sleep deprivation.

Why this matters for longevity

Chronic circadian mismatch is increasingly being linked to:

• metabolic dysfunction

• higher inflammation

• mood instability

• poorer cognitive performance

• increased long-term disease risk

We see this clearly in shift workers.

But we also see it in high-performing people who are living against their biology.

One of the most underappreciated optimisation moves is simply aligning sleep timing to your chronotype.

That means:

• identifying whether you’re naturally early, mid, or late

• adjusting your morning light exposure

• adjusting your training time

• adjusting your meal timing

• adjusting your evening routine

And yes, sometimes adjusting your work schedule if you’re in a position to do that.

Now, chronotype can be influenced. But it’s not infinitely flexible.

Genetics sets the baseline.

Lifestyle nudges the expression.

This is exactly why we include chronotype and circadian rhythm insights inside Life X DNA®’s Ultimate Pro report library.

Because once you understand your biological rhythm, you stop fighting yourself.

And that alone can be life-changing.

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How We Use Life X DNA® to Optimise Sleep (The Smart Way)

This is the part I want people to really understand.

Most sleep advice is generic.

And generic advice is fine… until it isn’t.

Because if you’ve already tried magnesium, sleep hygiene, and reducing caffeine, and you’re still waking at 2 am like clockwork, then there is usually something deeper going on.

With Life X DNA®’s Ultimate Pro Kit, we can explore things like:

1) Methylation efficiency

If methylation is sluggish, neurotransmitter clearance and stress regulation often suffer.

This can contribute to:

• racing thoughts

• anxious sleep onset

• frequent waking

• feeling “wired but tired”

Life X DNA® offers the most advanced and comprehensive methylation testing available, and this is one of the most overlooked links between sleep, mood, and longevity.

2) Neurotransmitter balance

Genes influence dopamine, serotonin, noradrenaline, and COMT activity.

This matters because sleep is not just about melatonin.

Sleep is about nervous system state.

3) Histamine pathways

Histamine is a wake-promoting neurotransmitter.

Some people have genetics that make them more prone to histamine sensitivity, and this can show up as:

• trouble staying asleep

• waking hot

• waking with anxiety

• night-time restlessness

4) Detoxification and oxidative stress

If detox pathways are underpowered, some people are more sensitive to:

• alcohol

• chemicals

• mould

• inflammatory foods

And sleep becomes lighter and more fragmented.

5) Inflammation susceptibility

Some people are genetically more prone to exaggerated inflammatory responses.

And inflammation and deep sleep do not coexist well.

This is why sleep optimisation is often an immune optimisation strategy, too.

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What I Actually Recommend (Without Turning This Into a “Sleep Guru” Post)

I’m not interested in making sleep complicated.

The goal is not perfection.

The goal is:

• stable sleep

• stable deep sleep

• stable circadian rhythm

• minimal fragmentation

Here are the highest ROI strategies I consistently see work.

1) Anchor your wake time first

Most people obsess over bedtime.

I care more about wake time.

If your wake time is stable, your circadian rhythm stabilises. Bedtime naturally improves.

2) Get bright light in your eyes early

This is one of the most powerful levers for:

• melatonin timing

• cortisol rhythm

• sleep onset

• deep sleep quality

Even 10 minutes outdoors helps. Not through a window.

3) Cool, dark, quiet bedroom

Deep sleep loves cool temperatures.

If you wake up at 2 to 4 am often, temperature and blood sugar are two of the first things I check.

4) Stop eating too late

Late meals raise core temperature and shift circadian timing.

A good target for most people is finishing food 2 to 3 hours before bed.

5) Watch alcohol

I’m not anti-alcohol.

But from a sleep architecture perspective, alcohol is one of the fastest ways to destroy deep sleep and increase fragmentation.

Even when you “sleep” longer.

6) Support magnesium and methylation pathways

This is where my world overlaps strongly with sleep optimisation.

Magnesium is foundational for nervous system stability.

And methylation efficiency influences neurotransmitter balance, including dopamine, serotonin, and noradrenaline.

If methylation is sluggish and stress neurotransmitters stay elevated, sleep quality suffers.

This is one of the reasons Life X DNA®’s Ultimate Pro Kit is so powerful for sleep optimisation. It allows us to stop guessing and start targeting the real drivers.

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The Big Takeaway: Sleep Is Not a Luxury. It’s a Longevity Strategy.

If you’re healthy and trying to optimise, sleep is not something you “fit in”.

It’s something you protect.

Deep sleep is where repair happens.
REM sleep is where integration happens.
Glymphatic clearance is where brain longevity is defended.
And fragmentation is where the whole system quietly breaks down.

And perhaps most importantly:

You can do every supplement protocol on earth, but if your sleep is unstable, your nervous system and immune system will never fully recover.

This is why sleep is often the first thing I work on with high-performing clients, even when their goals are weight loss, mood, energy, longevity, or cognitive performance.

Because sleep is the foundation those goals sit on.

And when the foundation is solid, everything else becomes easier.

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Want to Optimise Your Sleep Using Your Genetics?

If you’re serious about longevity, energy, and cognitive performance, and you want to stop guessing what your body needs, then I strongly suggest looking at Life X DNA®’s Ultimate Pro Kit.

It’s not just a DNA test.

It’s a full health optimisation system, built around:

• advanced methylation testing

• detox and oxidative stress pathways

• neurotransmitter and mood genetics

• inflammation susceptibility

• circadian rhythm and sleep timing genetics

• personalised supplement insights

• and access to over 1,200 health reports inside the Ultimate Pro library

And because it’s built to be practical, the goal is always the same:

Turn complex genetics into simple, actionable steps you can actually use.

If you’re ready to take sleep optimisation seriously, this is one of the smartest places to start.

Stay informed, stay healthy
Robert Van der Moigg
Founder – Life X DNA®