Thermal comfort:
Thermal comfort is how satisfied we are with our thermal environment when we’re sleeping and the three main factors that influence this are- Environmental climate, Clothing, Physical activity
Elements which alter the environmental climate include:
Air temperature (how hot the room is)
Thermal radiation (from bedding or a partner)
Air movement near the body (if there’s a window open or a draught)
Elements that dictate how our clothing has an effect on our environment:
Thickness of material and how it fits to our bodies
The insulation value of the garment and type of material
It’s resistance to the diffusion of water vapour (does it let our body breathe?)
Elements that may be categorised under physical activity include:
How much we move at night (relating to how deeply we sleep)
Our metabolic rate (how much energy our bodies are producing, normally when digesting food)
How does bedding affect these areas?
Bedding separates the microclimate of your bed and the ambient air temperature of the room. If you had no bedding then your temperature would be solely dependant on the ambient air temperature of the room bar what you were wearing.
This bedding barrier determines how much leakage of microclimate air travels into the ambient air of your room. This can either be through the upper layers such as a duvet or through your mattress as it conducts heat from your body into the room. If your bedding is leaking a large amount of your microclimate air into the room you will be cooler. Likewise, if it’s leaking little then you will be hotter.
The amount of leakage through a duvet is dependant on the thickness, the filling, how well the filling is able to retain air and insulate as well as how well the duvet adapts to your shape. This can also be said of your mattress.
Different fillings have different thermal properties so it is always worth enquiring about what materials in a product are likely to retain the most heat. How well the product adapts to your shape also contributes to what is called the ventilation effect. The ventilation effect determines how much air escapes from your microclimate when you move during sleep. Products that shape to your body such as duvets and memory foam products will have little ventilation effect, this creates a greater barrier between your microclimate and the ambient temperature of the room meaning you will be hotter during the night.
