Thermal Comfort

Temperature plays a critical role in sleep quality

If your body becomes too hot or too cold, sleep becomes lighter and more fragmented. Thermal stress can increase awakenings, shorten REM sleep, reduce deep sleep and elevate your heart rate. Moisture makes this worse. Sweat trapped against the skin creates a humid microclimate that increases heat build-up. Achieving the right core temperature drop at sleep onset and avoiding thermal stress during the night are key to optimising sleep continuity and depth.

The problem? Many of us struggle to stay the best temperature for sleep

1

%

of sleepers report temperature variation as their primary sleep disruptor (NSF)

1

%

report regularly being too hot while sleeping (Gallup, 2023)

1

%

report regularly being too cold while sleeping. (Gallup, 2023)

The science of thermal balance

Sleep, temperature and comfort are functionally linked.

  • If you become too hot or cold at night your sleep quality suffers.
  • Thermal stress causes micro-awakenings & pulls you out of restorative sleep.
  • By staying in your climatic comfort zone (staying thermally “neutral”) you can sleep deeper for longer.
  • Even small deviations from your ideal thermal range can pull you out of deep, restorative sleep often without you even realising.
  • Night sweats can also lead to discomfort & awakenings.

How much do we sweat at night?

How much do we sweat at night?

During a night’s sleep you lose an average of 240ml moisture through sweating

What happens during REM?

What happens during REM?

During REM sleep your body’s ability to regulate temperature is impaired

How much do we sweat at night?

During a night’s sleep you lose an average of 240ml moisture through sweating

What happens during REM?

During REM sleep your body’s ability to regulate temperature is impaired

Achieving the right core temperature drop at sleep onset and avoiding thermal stress during the night are key to optimising sleep continuity and depth.

The bottom line

For your best quality sleep, you need to get cool and stay cool.

How Zed can help you

Zed sleepwear is built to support thermal balance by helping you stay in your “sweet spot” all night. Our advanced natural fabrics are exceptionally breathable and use a dual-cooling mechanism that draws moisture away from your skin and allows heat to evaporate efficiently.

The goal is simple: Enter your climatic comfort zone. Stay there.

How it works

ZedCore™ fabric is engineered using Micro technology to stabilise your skin microclimate through a natural moisture-management process.

1. Moisture wicking

Ultra-fine Micro Modal fibres absorb sweat quickly

2. Evaporative cooling

The fibre structure disperses moisture evenly

1. Moisture wicking

Ultra-fine Micro Modal fibres absorb sweat quickly

2. Evaporative cooling

The fibre structure disperses moisture evenly

3. Moisture release

Evaporation releases heat from the fabric surface

4. Skin comfort

Helping maintain your ideal skin micro-climate

3. Moisture release

Evaporation releases heat from the fabric surface

4. Skin comfort

Helping maintain your ideal skin micro-climate

Although traditional fabrics such as cotton or silk absorb sweat, they are very poor at evaporating that sweat away. The nanostructure of our advanced fabrics uses a dual cooling functionality that pulls moisture away from your body quickly & moves it to the fabric exterior for evaporation at the perfect speed to help you cool down.

Independent textile testing shows significantly higher breathability and faster moisture release compared to conventional cotton fabrics. The difference is structural. Moisture management is built into the fibre itself, not applied as a chemical finish. This performance remains wash-stable over time.

The result?

You stay in your ideal climatic zone to support a deeper & longer sleep.

Latest supporting research

The connection between thermoregulation, comfort & sleep quality is one of the best-documented findings in sleep medicine. Achieving the right core temperature drop at sleep onset and avoiding thermal stress during the night are key to optimising sleep continuity and depth. Some notable peer-reviewed studies are listed below.

Core Temperature Decline

Our bodies must cool down by about 1 - 2 °C at night to trigger and maintain deeper sleep. If we can’t dissipate heat effectively, sleep onset is delayed.

Ref: Kräuchi, K. (2007). Sleep Medicine Reviews, 11(6), 439–451.

Disrupted Sleep Architecture

Overheating or being too cold causes frequent awakenings and reduces time spent in slow-wave (deep) and REM sleep, hindering physical recovery and memory consolidation.

Ref: Harding, E. et al. (2018). Current Opinion in Physiology, 5, 1–8.

REM (Rapid Eye Movement) Sleep Sensitivity

During REM, the body’s ability to regulate temperature (e.g., shivering or sweating) is significantly reduced. As a result, if the sleeper becomes too warm, there’s an increased risk of early awakenings or abrupt stage transitions, cutting REM short.

Ref: Harding, E. et al. (2018). Current Opinion in Physiology, 5, 1–8.

SWS (Slow Wave Sleep) Preservation

Even a slight bump in temperature e.g., a few degrees over your comfort zone can diminish SWS by 5 - 10%. This might seem small, but losing even that fraction of deep sleep can reduce the overall restorative impact of the night.

Ref: National Sleep Foundation (2024). Temperature and Sleep. 2024 Data & Polls.

Thermophysiological Cascade

Dilated skin vessels in hands and feet accelerate heat loss, promoting faster sleep onset. Heat loss via skin vasodilation is the “cement” that binds the circadian clock to sleep initiation. Core cooling and distal warming (hands and feet) are physiological prerequisites for healthy sleep onset.

Ref: Kräuchi, K. (2007). Sleep Medicine Reviews, 11(6), 439–451.

Humidity Factor

In high-humidity settings, sleepers tend to overheat more easily, resulting in fragmented REM and SWS. This effect leads to more frequent awakenings and reduced total time spent in restorative stages.

Ref: Wang, T. et al. (2020). Impact of humidity on sleep and thermoregulatory behavior. Sleep Health Journal.

Night Sweats & Trapped Moisture

Excess perspiration or damp fabrics trap heat at the skin, elevating body temperature and forcing micro-awakenings.

Ref: Chow, S. et al. (2019). Nature and Science of Sleep, 11, 201–214.

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