Hi Jayne.

The heat aspect associated with Memory Foam is well and truly documented.

Over the past few years various solutions to this problem have been introduced such as utilising Coolmax fabrics as the covering (Outlast is another) but I am personally quite cynical about the claims made.

Other techniques to reduce the heat element includes channelling the memory Foam and the underlying foam support layer to encourage the free flow of air through the mattress.

Once again, my cynicism kicks in and I feel it is unlikely that this has a significant impact on the heat build up.

Logically, one would assume that for air to flow freely through the mattress there has to be some kind of venting system.

If your mattress has a sheet plus bedding this free flow of air would be considerably hampered.

I personally think heat reduction should be via your bedding.

The reduction in tog value of your duvet helps considerably and also you can purchase Coolmax / Outlast bedding which offers a greater degree of benefit than having it directly on your mattress.

Hope this helps.

Kind Regards Gary