- But shouldn't you be resting, Kay?
- I couldn't sleep.

5 seconds sound clip from the Creature from the Black Lagoon (1954) movie soundboard.

You can hear this line at 00:55:26.373 in the Blu-ray version of the movie.

Quote context

[...]

- Oh, Doctor, would you mind staying behind and keep an eye on our prize?

- Don't be long, David.

- You better get some rest.

- Hi. I thought I'd come up and get some air.

- What do you suppose is taking them so long?

- David's very thorough.

- But shouldn't you be resting, Kay?

- I couldn't sleep.

- Listen to the sounds.

- Hunting calls, mostly. Animals out for the kill.

- Some of them are cries of fear, like people who whistle in the dark.

- I'm not exactly blind. You're worried about what's happened between Mark and David.

- But once you admit the simple fact that you're in love, which you have, then it becomes a good idea to be the scientist about it.

- It's not as easy as that.

- Why not?

[...]