Special lights that change colour are to be tested by Nasa to help astronauts sleep better on the International Space Station.
In space, there isn't the usual day and night cycle that human bodies are used to on Earth - and that can make it difficult to nod off.
So it's hoped that lights which switch between blue and red will help tackle the problem.
Blue light can make you be more alert, while red encourages a sleepy feeling.
Lack of sleep can cause depression, sickness and make mistakes more likely.
Nasa has spoken before about astronauts suffering from sleeping problems on space missions, with many having to take sleeping pills.
The new lighting is due to be tested in 2016.