Yes it does but others will also say "nothing happened to my babies, they turned out just fine". It doesn't affect them in a way to totally ruin your yield it just does a small affect because it changes the internal chemical process of your plants when they thought it was going to be dark or light but it wasnt. Stay to the same schedule and do your best to not interrupt the cycle or have ANY light leaks during darkness. dont worry, happened to me 4-5 times and im a first time grower (mine look great)...best of luck =))