in the dark 在黑暗中，无知，不知

【例句】
When your brain is still in the dark, it keeps your appetite high* and you continue eating.
你的大脑并不知情，就继续使你胃口大开然后你就继续吃。

I had to feel about in the dark for the light switch.
我得在黑暗中摸索寻找电灯开关。