There are 7 light bars (6 white, 1 color) and each represents a percentage of your step goal completed. So at the beginning of the day, only one white light bar will light up. Once you have reached your goal, all the lights will light up, as well as the colored light.
When you put your Band into sleep mode, the lights will go through a special animation: All 7 lights will blink 3 times, the color LED is Blue. On the third blink the lights will turn off, progressing from the outside lights in.
If you tap your Band while in sleep mode, only the middle two white lights will pulse.
Once you turn sleep mode off, the Band will go through the same animation but in the reverse order- the two center bars will blink 3 times, then the rest of lights will turn on from the center out.
When you are completely out of sleep mode the color light will change from blue to green.