It goes deeper than that. They're behaving strangely. They appear to be troubled. They don't care to sleep.
7 seconds sound clip from the Santa Claus Conquers the Martians (1964) movie soundboard.
You can hear this line at 00:09:03 in the Blu-ray version of the movie.
Quote context
[...]
- And Kimar is very angry, too.
- I bought some new food pills. I hope the children will eat these.
- I'm worried about our children.
- So am I. They've hardly eaten a thing in three days.
- I had to use the sleep spray on them again.
- Something is happening to the children of Mars.
- As leader of the Martians, you must do something about it.
[...]