Sleep Efficiency ≥85%
When was the last time you actually considered how much of the night you spent asleep — not just how long you were in bed?
It’s been known on occasion that when checking in with a clients prior to beginning a session, they’ll often tell me, “Yeah, I got about seven hours last night.” If they’ve got the capacity, we’ll then take a quick look at the data — Apple Watch, Oura Ring, Whoop Band, whatever type of wearable they’re using — and it’s likely closer to five and a half hours of actual time asleep, ~60 minutes awake in segments across the night, and a resting heart rate that’s sitting 8-10 beats higher than normal in the morning.
That’s starting to look a lot less than a healthy 7-8 hours, and moving closer towards “just getting enough to get by.”
And here’s the thing nobody really likes because the concept of sleep isn’t all that sexy: this pattern isn’t just why you’ll likely feel tired tomorrow. It’s the pattern that also has the capacity to silently speed up blood pressure problems, stubborn midsection weight gain, and cognitive decline risks later in life (Cappuccio, 2011; Xu, 2020).
You may just be considering it as if it’s a “rough patch” you're working through. Your body is likely to see it more like an issue of chronic stress.
To get a better understand, we can look to apply a boring, brutal, but inevitably honest metric: Sleep Efficiency.
Not how long you were in bed. But how much of that time you actually spent asleep.
Because that one number — sitting above or below ~85% — tells you more about both short-term performance the next day, and long-term independence in laters years, than most people realise.
What Sleep Efficiency Actually Is (and Why 85% Matters)
Sleep efficiency as a concept, is incredibly simple: of the time that you were in bed, how much of it were you actually asleep?
Example: you’re in bed, lights off, with the intention of sleeping from 23:00 to 07:00. That’s a potential window of 8 hours in bed. Regardless of what tracking device you may or may not be using, if you actually slept for 6 hours and 15mins of that time period, your sleep efficient is roughly 78%. Under the 85% line.
Why does this matter?
Because if you’re dropping under ~85% consistently, you’re not just a “light sleeper by nature.” You’re spending a big chunk of the night itself awake, restless, or still half-alert. That matters today, and it also matters in 20 years…
So from an immediate performance perspective, low sleep efficiency shows up in the A.M as a higher resting heart rate, higher perceived effort in training, worse control of cravings, and a shorter fuse with the people you care about the next day. If you’ve ever had a training session suddenly feel heavy for no good reason, sleep efficiency is often one of the first places we’ll look.
From a longevity and health-span perspective, chronically poor sleep is linked to higher blood pressure, poorer insulin sensitivity, and worse long-term brain health in middle-aged and older adults (Cappuccio, 2011; Xu, 2020).
They’re the factors that likely determine whether you’re independent in your 70s and 80s — memory intact, emotionally stable, moving without fear of tripping or falling — not whether you still look lean at 42.
This is the pattern we’re most likely to see:
Under-slept at 35 = you’re just tired.
Under-slept at 45 = you’re likely heavier, more irritable, BP creeping upwards.
Under-slept at 65 = you’re likely more fragile, emotional regulation is wobbling, and confidence in day-to-day living is dropping.
It’s the same behaviour. The costs are just continuing to compound.
WASO: The Quiet Red Flag Often Untracked
Another term we can consider important here is WASO - Wake After Sleep Onset.
That’s the total time you spent awake in the middle of the night.
If that number is regularly above ~30 minutes, without a specific reason, you’ve got friction in the system against sleep. Sometimes you may remember it (eg., staring at the ceiling at 03:40, dreading the presentation you’ve got to give the next day). Sometimes you don’t, because most likely you dipped in and out briefly five, six, seven times across the night.
Here’s why it matters:
If you’re waking for long periods in the night, you almost always see knock-on effects the next day that are hard to ignore: more hungry, more emotionally volatile, higher rating of perceived exertion in training (even with an identical session to the previous week). That’s not a “weak mindset.” That’s literally just the physiology of sleep, and more specifically, sleep deprivation.
You also tend to see less REM and less slow-wave “Deep” sleep — the portion of sleep that handles things like emotional processing, tissue repair, hormone regulation, learning, memory consolidation, basically everything that stops you from feeling like a walking threat-signal the next day.
Whilst there are obviously caveats against how accurate devices such as an Eight Sleep mattress, Oura Ring, or Whoop Band, are at parsing out these sleep stages, high-level sleep studies such as those cited in the Matthew Walker book “Why We Sleep” support the claims, even if the tracking sensitivity isn’t quite there yet commercially.
So when you say “I’m just not recovering,” between sessions or workouts, WASO is another area we’re likely to start to consider.
“I’m training hard but I can’t seem shift this body fat” (i.e. Sleep Debt)
By the time most individuals hit their 40s and 50s, the sleep game changes.
In your 30s, and I can attest to this myself, you can to some extent under-sleep, be woken multiple times by children through the night, rely on pre-workout caffeine to get through a gym session, eat on occasion chaotically, and to some extent your body will more or less plays along.
In your 40s and 50s, the exact pattern (under-sleep, frantic days, high stress, poor eating patterns, late collapses into bed) are more likely to show up as:
Stubborn body fat around the midsection.
Blood pressure quietly creeping up.
Feeling exhausted but somehow still “wired” at bedtime.
Shorter than usual temper, for no reason.
Training sessions that feel “heavy” even though you haven’t increased the load or volume.
Again: this isn’t a mindset issue you can just “push through”. It’s also not just “something that happens with ageing”. A lot of the time, it’s unaddressed unregulated sleep patterns.
Sleep restriction — especially when chronic — has been associated with increased blood pressure, worse insulin sensitivity and blood glucose control, and higher perceived stress loads in adults, even without a change in anything to do with nutrition (Tasali, 2008; Knutson, 2009). Over years of restriction, that becomes your cardio-metabolic story: pre-diabetic trends, higher cardiovascular risk factors, slower recovery, more inflammation.
In simple English: if you ignore sleep efficiency in midlife, you’re basically running rehearsals for the version of you who’s going to be struggling in their 60s and 70s.
This is why it’s so important to remember: your sleep is not “recovery”. Recovery is the output, sleep is the input.
Snoring, Apnoea, and “I pass out fine, I just wake up wrecked…”
One of the intake questions we ask clients is the plain and simple, “Do you snore at night?”. In the UK especially, a lot of men and women in their 30s, 40’s and 50s laugh it off. “Yeah, I snore my partner hates it”. As if it’s just something that happens, nothing to see here…
Whilst it’s an individuals choice to laugh it off, or see it as a health concern, what actually matters is this: are you repeatedly stopping breathing for short bursts while you sleep, dropping oxygen, generating micro awake times all night, never truly able to get stable deep sleep?
That’s a little more than just “snoring”. That’s far more likely to be verging on sleep apnoea.
Sleep apnoea isn’t just something you or your partner might find an annoying quirk. It’s a cardiovascular and cognitive risk factor. It’s associated with high blood pressure, impaired attention and memory, and daytime fatigue that you may recognise as “I just can’t seem to focus like I used to.” If it goes unrecognised, and untreated, it can absolutely wreck sleep efficiency over not just a few nights, but over years, and decades (Punjabi, 2008).
Here’s the reality inside the UK. Approximately 42% of the UK adult population snore. That’s 15 million people. This number jumps to >55% in those over 60 years. So if you’re snoring loudly, waking unrefreshed, and/or you or your partner notices pauses in breathing, that’s not a sign to “get a better pillow”. That’s more like: book in with your GP and have an honest conversation about what’s going on.
NHS sleep studies exist. CPAP (pressured air to keep the airway open) isn’t vanity gear. It’s much more like a recognition that I’d like by brain, heart, and mood regulation still to work in 20 years time.
Short-term view: “I’m fine, I’ll get through the day”.
Long-term view: “You’re quietly starving your brain of oxygen 200 times a night and pretending that everything’s still OK.”
Two very different games…
Caffeine, Alcohol, and the Two-Hour Window Trap
If we wanted to be adult about the conversation, most individuals don’t intentionally wreck their sleep because they deliberately want to harm their health. Much more likely is they have coping strategies (or lack therefore of…) that don’t align with positive sleep behaviours.
So after a long day, work and home stress, you want to decompress and unwind. Completely reasonable. That may be a glass of wine, a few snacks while watching the T.V, or possibly you’re scrolling social media at 22:45 because you just wanted to check one last time. Then bed.
But there’s an obvious cost to this type pattern:
Caffeine has a long half-life. So an espresso or pre-workout energy drink at 17:00, will still have half of the caffeine amount in your bloodstream at 23:00. You may feel that you fall asleep fine, but there’s an increased likelihood that you’ll wake up again during the night with the inability to full switch down into deeper sleep. That results in a higher WASO, lower sleep efficiency (<85%…) and possibly higher irritation overall the following day.
The effects that alcohol and blue spectrum light (the type emitted from our phones, T.V’s and devices) have on sleep is well established. We know it causes fragmentation in sleep overall, reduces REM, and slow-wave “deep” sleep, even in moderate doses, and especially when close to bedtime. You may feel that you fall asleep faster, but the sleep you do get is likely to be significantly lower quality, more broken, and less restorative. Again, WASO up, efficiency of sleep, down.
Go back again to what gets taxed when deep sleep is reduced: tissue repair, hormone regulation, emotional reset. Which means again, that training sessions feel worse for the same of lower output, cravings likely increase, and our overall patience collapses.
This is where the short-term vs long-term split becomes obvious.
Your shorter-term brain may be telling you: “I deserve to relax, I’ve earned it.” And no doubt you do deserve it…
But your longer-term brain is likely to be saying: “If this becomes my default pattern for the next decade of so, I’m playing with my metabolic health, my blood pressure, by mood stability, brain ageing, and likely my relationships with those around me.”
The Two-Hour Window to Change Everything
There gets to a time in the evening for all of us, where most adults never defend: the two hours before the lights go out for bedtime. For most working individuals within the UK, that’ll fall most commonly between 22:00 and 00:00.
This is the window of time where we actively get to decide if we’ll hit:
A Sleep Efficiency of >85%.
A WASO <30mins.
≥7 hours of real, undisrupted sleep.
A resting heart rate that reflects your true cardiovascular health.
Whilst the likelihood of ever achieving perfection on these measures is slim, we have far more control over the general direction that things are moving in.
So choosing to take charge of that two-hour window could look something like the following:
Stop Intake: Food, caffeine, alcohol - give your digestive and nervous systems time to make the much-needed downshift ahead of bedtime.
Reduce Stimulation: This could be screens of any type, difficult or challenging conversations, work emails, social media doomscrolling.
Actively try to reduce heart rate: This could be through reading, meditation, simple box breathing or breath work, anything that starts to active shift you away from the “fight or flight” and into the “rest and digest”.
The goal becomes to arrive into your bed already descending, not your head hitting the pillow and you’re still running at a 100mph, with no mechanism for slowing yourself down.
Most individuals tend to do the opposite. We’re high alert in all our pre-bedtime behaviours, we watch TV shows that ramp up our nervous systems, we’re still snacking 15-20mins before our bedtime, or we’re unable to remove ourselves from “work-mode”without responding to every email that came across our path that day. We then get into bed and expect to just “sleep now please”.
The system doesn't work like that unfortunately.
Think of it this way: your pre-bedtime routine is worth an order of magnitude more for sleep efficiency that any supplement you may be tempted into buying.
Priorities by Decade: Sleep is Not Equally Negotiable…
In your 30’s?
You’re likely to still be able to get away with disrupted sleep habits, kind of…
You’ll likely be able to miss a few nights of quality sleep and see limited impact on cognitive functioning and training performance. It’s most often the time period in which life gets most in the way of sleep quality and quantity (think young children, work demand etc…) That’s not to say it’s a free invitation to cut back, it just means that the bill hasn’t arrived at the table yet.
In your 40s-50s?
This is where you’re likely to start to see the signs of sleep inefficiency in the form of impact on health metrics such as blood pressure, body composition, and training recoverability. For females, this can also be the time period in which hormonal changes associated with menopause can begin to disrupt the consistency of sleep metrics. As we touched upon previously, this is also the decades in which sleep disrupted behaviours, or patterns, start to become most normalised, so instead of seeking a treatment for snoring, we accept it as just the way things are going to be moving forward.
In your 60’s+
Now the cost of sleep disruption is actual function. Poor long-term sleep is associated with worse cognitive performance, mood instability, balance issues, and general frailty in older adults (Xu, 2020). At this time point, we’re not talking about just feeling fresh in the morning, we’re talking about independence: can you manage the later years of life without fear, confusion, or falls?
This is why sleep is so much more than just recovery when we consider the downstream effects across the lifespan. It’s fall prevention. It’s cognitive protection. It’s the ability to play (and hopefully win…) a board-game against your grandchildren. It’s your emotional floor. It’s the ability to re-tell stories, give guidance, and keep an independent mind across your lifespan.
If you’re treating sleep like an optional extra in your 30s and 40s, you’re borrowing quality of life from your 60s and pretending that it’s free.
The REAL Question to Ask Yourself Tonight
So we can start to forget the “Did you get eight hours?”. It’s too vague, and too easy to lie to ourselves about if truth be told.
Instead, we can begin to ask ourselves:
Did I actually get ≥ 7 hours of time spent asleep, not just in bed.
Was my sleep efficiency ≥ 85%?
Was my WASO (Wake After Sleep Onset) under 30 minutes?
Did I wake with a resting heart rate that doesn’t look like I was chased by a predator through the night?
If the honest answer is “no”, then you haven’t failed. This is important to recognise. It’s not win/lose. You just haven’t yet found your next highest-leverage target.
And, let’s be truly honest, it’s not going to be found in another supplement. Nor is it not another blue-light blocking gadget.
It’s likely going to be down to one of four things:
You're not giving yourself a distinct two-hour window to ease into your sleep routine.
Your caffeine consumption is drifting too late into the day, or is a higher than optimal dose considering its half-life.
You’re carrying work stress, and possibly alcohol consumption, with you right up until bedtime.
You may need to contact a GP about snoring/apnoea instead of normalising it.
Remember, your role here is to see the pattern in black and white. Not to make judgement against any behaviours. Good sleep begins when you choose to take part.
A Challenge For This Week
Try this for the next 7 nights: Track these four numbers/observations, even if it’s just notes inside your phone…
Time in bed (eg., lights out to lights on).
Estimated time actually asleep.
How long you were awake in the middle of the night (a rough guess is fine here…)
How you felt getting up: calm and well-rested, or already tense and irritable?
Takeaway for life: Sleep shouldn’t be considered a sign of laziness. The often cited mantra of “I’ll sleep when I’m dead” is ironically going to lead to a shorter lifespan in the end. Sleep is self-respect. It’s recognising that you value your health span (how healthy you are as you age) as much as your lifespan.
Important Note: This article is written for purely informational purposes for clients and followers of Integrative Fitness Training and the IFT Edge Substack Page, and is not meant as medical advice. If you’re dealing with loud snoring, choking/gasping during your sleep, in very high daytime sleepiness, or consistently elevated morning blood pressure or resting heart rate, please do speak to a GP.
AK.