LEDs do not disrupt sleep. It is the Blue and the Green color of the light that has some effect on the sleep quality. Red is observed to have the least amount of impact on sleep quality.
The shorter wavelength of light like blue light, suppress the production of a hormone called Melatonin, which is responsible for our sleep. In other words, a person who is subjected to blue light before sleeping will shift his cardiac rhythm 3 to 4 hours. That means, he will feel sleepy 3 to 4 hours after the normal time he goes to sleep. Plus, he will not get stage 4, deep sleep which is crucial for a healthy body.