Is it safe to take ambien (zolpidem) that has been stored in the dark for a little over a year?

Yes, in general: If stored under good conditions (appropriate temperature and humidity and light) the medicines are supposed to maintain their potency at least through their experation date (printed on the label). Over time all chemicals can deteriorate. That's most important to be careful with meds for serious conditions such as seizure disorders or high BP. Ambien (zolpidem) is just to make you sleepy, not so serious.