Readers  -   it really helps me to know your age and where you live for climate reasons!!!  On this one, it depends partly on whether you live in a sunny climate or spend a lot of time outdoors.  I love tretinoin (Renova, Retin-A) as you all know for the reasons mentioned in my book and on this site.  But, it does thin the outer, dead layer (the stratum corneum) a little, as does the Clarisonic.  This does make you a bit more sun sensitive.  So, if you're not outdoors much that's probably not a problem.  If you are, you might need to adjust one or both and be very compulsive about sunscreening.

 The Clarisonic is very gentle and it's usually not a problem to use it once daily.  Don't use other scrubs with it though and if you start noticing a dry, dull appearance again, you are over exfoliating and need to back off to get the glow back.