Is there any reason why I shouldn't leave a face mask on overnight?

[WendyWithers]

I use lovely, moisturising Elemis and Clarins face masks and it always seems such a waste to rinse them off after 10 minutes.

Would anything awful happen to my skin if left them on my face and neck overnight?

The Elemis one you can massage in and leave on anyway - should say in the directions if it's the one I'm thinking of.

Haven't tried the Clarins one but I'd say give it a go, or wipe off the excess (and rub into your arms) and massage the rest in.