Hi Jan,

Sleeping on a new mattress does take a few nights, in some cases, weeks to get used to.  It's a bit like a new pair of shoes.  Sometimes the new mattress is a bit of a shock to the system and over heating can be one of the short term problems.

Overheating on mattresses is a common issue and because everyone is slightly different it's hard to have an exact rule. That said certain materials such as memory foam should be avoided if you know you are a hot sleeper.  This is because certain materials like synthetic heat retentive foams trap and contain heat more than natural breathable materials.

Latex is slightly different as 100% natural latex is breathable and far less heat retentive than memory foam or other synthetic components.  However for some people latex is still too warm.
 

Without knowing the exact model or blend of latex it's hard to advise other than to say try changing the tog of your duvet and make sure you give the bed a week or two to settle into.  Unless it's unbearable that is!  Some entirely synthetic blends of latex will retain more heat than their natural counterparts.

Thanks