Sleep Optimisation & Temperature: The Science, Signals, and Easy Wins

Sleep Optimisation & Temperature: The Science, Signals, and Easy Wins

Why sleep optimisation matters (and why it’s not just “sleep more”)

Sleep is one of the most underrated performance tools we have. It affects energy, mood, appetite regulation, recovery from training, skin health, immune resilience, and even how patient we feel with the people we love.

When clients tell me they’re doing “everything right” (training, steps, nutrition) but still feel flat, the missing piece is often sleep quality;  not just sleep quantity. And one of the biggest levers for sleep quality is temperature.

In this two-part series, we’ll cover:

  • How body temperature and sleep are linked
  • Why being cooler at night can support deeper sleep
  • Practical tools you can use to optimise your sleep environment
  • Real-world case studies (client-style scenarios) showing what actually moves the needle
  • Cooling bedding upgrades I personally love and use.

The simple physiology: sleep and temperature are inseparable

Your body runs on a 24-hour internal clock called the circadian rhythm. One of the clearest signals your body uses to decide whether it’s time to be alert or time to sleep is core body temperature.

In the evening, your body naturally starts to cool down. That drop in core temperature helps trigger sleepiness and supports the transition into deeper sleep stages.

Core temperature vs skin temperature

A key nuance: you don’t need to feel cold. The goal is to support a gentle drop in core temperature.

Your body does this by increasing blood flow to the skin (hands/feet), letting heat escape.

That’s why people often sleep better when: - The room is slightly cooler - Bedding is breathable - They aren’t overheating under heavy duvets

Overheating is a quiet sleep disruptor

If you’re too warm at night, you may:

  • Take longer to fall asleep
  • Wake more often
  • Spend less time in deep sleep
  • Feel unrefreshed even after “enough hours”

And for many women (especially with hormonal fluctuations), temperature sensitivity can be a major factor.

What “cool” actually means for sleep

There’s no perfect temperature for everyone, but most people do well with a cool bedroom and breathable bedding.

A practical way to think about it:

  • If you wake up sweaty or kick the duvet off repeatedly → you’re likely too warm
  • If you wake up tense and shivery → you’re likely too cold
  • If you wake up comfortable and steady → you’re in the zone

The goal is stable comfort.

The sleep optimisation pyramid (how I prioritise changes)

If you want the biggest return on effort, I like to work from the base up.

1) Environment (the “set and forget” wins)

  • Temperature
  • Light
  • Noise
  • Bedding comfort

2) Behaviour (the daily habits)

  • Consistent sleep/wake time
  • Caffeine timing
  • Alcohol impact
  • Evening routine

3) Physiology (what’s happening internally)

  • Stress load
  • Training timing
  • Blood sugar stability
  • Hormonal considerations

Temperature sits right at the base because it’s one of the easiest changes to make that can create immediate improvement.

Tools you can use to optimise sleep

Here’s a menu of tools; you don’t need all of them. Choose what fits your lifestyle.

A) Bedroom temperature tools

  • Thermostat programming: set a cooler temp 60–90 minutes before bed
  • Fan: even if it’s not cold, airflow helps heat dissipate
  • Window strategy: crack a window (if safe/quiet) to drop room temp
  • Dehumidifier (if you live somewhere humid): humidity can make you feel hotter and disrupt sleep

B) Light and circadian tools

  • Blackout blinds/curtains
  • Low warm lighting after sunset
  • Morning daylight (10 minutes outside early in the day is a game changer)

C) Tracking tools

Tracking can help you notice patterns, but it can also create anxiety if you obsess.

  • Wearables (Oura, Whoop, Apple Watch)
  • Simple sleep diary (bedtime, wake time, caffeine, alcohol, workout)

If tracking stresses you out, skip it. Your energy and mood are data too.

Practical temperature strategies you can try tonight

1) The “warm shower, cool room” combo

A warm shower or bath 60–90 minutes before bed can help because when you step out, your body releases heat and cools down.

2) Layer your bedding like a wardrobe

Instead of one heavy layer, use:

  • A breathable duvet
  • A lighter throw you can add/remove

This reduces the “too hot / too cold” cycle.

3) Cool your feet

If you run hot, cooling the feet can help the body offload heat.

Simple options:

  • Lighter socks or no socks
  • A thinner blanket at the foot of the bed 

Build a Cooler Bed Setup (Pillow, Duvet, Protector)

The goal: a cooler “sleep microclimate” (without feeling cold)

When people think about sleeping cool, they often imagine a freezing room and no duvet. In reality, the best sleep setup is usually about creating a stable, comfortable microclimate in the bed.

Your body needs to drop core temperature slightly to fall asleep and stay asleep. If your bedding traps heat, you can end up in the classic cycle:

  • fall asleep fine
  • wake up warm (or sweaty)
  • kick covers off
  • wake up cold
  • pull covers back on
  • repeat

So the goal is not “cold.” It’s consistent comfort.

Step 1: Start with the pillow (because your head runs hot)

Your head and neck are often where people feel heat build-up first. If the pillow traps warmth, you’ll toss, turn, and flip it constantly searching for the “cool side.”

What a good sleep pillow should do:

A pillow should support two things at the same time:

  • Temperature regulation: it shouldn’t trap heat around your face/neck
  • Alignment: it should keep your neck in a neutral position so you’re not waking with tension

If you wake up with:

  • a stiff neck
  • headaches
  • jaw tension
  • a feeling you can’t get comfortable

…your pillow is often the first place to look.


Product I genuinely rate: TEMPUR Cloud Air SmartCool™ Medium Pillow

This is one of those upgrades that feels subtle at first, and then you realise you’re waking up with less tension and fewer night wake-ups.

What I personally like about it (in an educational, non-salesy way):

  • SmartCool™ cover: helps reduce that warm, sticky feeling around the face and neck - Medium feel: supportive without feeling overly firm (a good “middle ground” for many sleepers)
  • - Comfort consistency: less “pillow flipping,” more settling

If you’re a hot sleeper, or you wake up feeling like your head is too warm, a cooling pillow cover can be a surprisingly big win.


Step 2: Choose a duvet that doesn’t trap heat

A duvet can make you feel cosy, safe, and relaxed; but it can also be the main reason you overheat.

Signs your duvet is too warm

  • You wake up sweaty (even if the room is cool)
  • You kick the duvet off multiple times a night
  • You feel “stuffy” or restless
  • Your sleep is lighter in the second half of the night


What to look for in a cooling duvet

  • Breathable fibres
  • Moisture management (less clammy feeling)
  • A feel that’s still comforting (so you don’t end up sleeping uncovered)


Product I love for this: Home by TEMPUR® Luxe Fibre Cooling Duvet

I like this style of duvet because it supports the “cosy but not overheated” sweet spot.

Why it can support sleep quality:

  • Helps reduce the overheating that drives micro-wake-ups
  • Makes it easier to stay in that stable comfort zone through the night
  • Works well with the layering approach (duvet + optional throw)

 

Step 3: Don’t ignore the mattress protector (it can trap heat like a raincoat)

Mattress protectors are underrated and some of them are basically a heat-trapping barrier.

If you’ve ever thought: “I have nice sheets, but I still feel hot in bed,” …your mattress protector could be the reason.

What a good protector should do

  • Protect the mattress (obviously)
  • Stay breathable
  • Help manage moisture
  • Avoid that plastic-y, sweaty feeling

Product I personally like: TEMPUR® Cooling Tencel Mattress Protector

This is a great option if you want to improve the feel of your bed without changing your mattress.

Why it can help sleep:

  • It’s right under your sheet, so it directly affects how the bed feels
  • Cooling + moisture management can reduce night waking
  • It’s a practical upgrade that supports long-term mattress care

 

How to build your “cool sleep setup” (simple upgrade plan)

If you want a straightforward plan, here’s the order I’d do it in.

Option A: The quick win (start here)

  1. Cool the room: thermostat down slightly, add airflow
  2. Layer bedding: avoid one heavy “heat trap” layer

Option B: The comfort upgrade (best value)

  1. Cooling duvet (biggest impact for overheating)
  2. Cooling pillow (big impact for comfort and neck support)

Option C: The full sleep microclimate reset

  1. Cooling mattress protector (fix the base layer)
  2. Cooling duvet
  3. Cooling pillow

Temperature + habits: the combo that makes it stick

Cooling bedding is powerful, but the best results come when you pair it with a few simple habits:

  • Consistent wake time (even more important than bedtime)
  • Caffeine cut-off (many people do best stopping 8–10 hours before sleep)
  • Dim lights in the evening
  • Warm shower 60–90 minutes before bed
  • Morning daylight (10 minutes outside)

You don’t need perfection - you need consistency.

Quick “cool sleep” checklist

  • I wake up hot or sweaty
  • I kick the duvet off repeatedly
  • I flip my pillow to find the cool side
  • I feel like my bed is warmer than the room
  • I sleep better in a cooler hotel room

If any of these are true, you’ll likely benefit from cooling your sleep setup.

Sleep optimisation doesn’t have to be complicated. If you want to feel more rested, recover better, and have steadier energy, start with temperature.

A cooler room helps,  but the real magic is building a bed setup that keeps you comfortable all night long.

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