I've taken cyclobenzapine since yesterday evening until just now... i think valium has been better for me in the past. can i switch to valium tonight?

OK though caution: While there are no serious interactions between these, there can be an additive effect making you more drowsy/dizzy etc. It takes about 18 hours to eliminate half of cyclobenzaprine so you will still have some in your system for a couple days, but it should be safe as long as you know you might have more drowsiness than usual.