What does the highlighted parts mean in the following passage?
Light striking your eyes is the most influential zeitgeber. When researchers invited volunteers into the laboratory and exposed them to light at intervals that were at odds with the outside world, the participants unconsciously reset their biological clocks to match the new light input. The circadian rhythm disturbances and sleep problems that affect up to 90% of blind people demonstrate the importance of light to sleep/wake patterns.
At intervals means occasionally but we don't know if all exposed durations are long equally.
"At odds with something" means "in disagreement" so volunteers exposed to light in nights but did not expose to light in daytime, it is kind of contrary to light outside.
Is this right?