Possible to tell how long youve been in your LD

Is it possible to know how long you have been inside of your lucid dream? I think it would be cool to see how long all of your LDs are and then compare, or is it more of a guessing game

If you mean dream time, then you can feel it or even control it, depending on the dream it might be easier if dream is perfectly stable. :zzz:
If you mean an actual sleep time then i heard there are some devices/goggles with leds that you can see from the dream, but i am not sure. :-?

Maybe I'll imagine a time in my dream and tell it to tell me how long I've been inside the dream, doubt it will work though

I can imagine a programmable eeg device such as emotiv being set up to read the time when a certain brainwave pattern is recorded, when you want to know the time you will the thought that triggers the program, then hear it in your dream through earphones connected to your sleeping body.