Fitbit Flex™ features five LED indicator lights. The lights behave differently depending on what the tracker is doing.
The indicator lights illuminate as you hit 20% increments towards your goal. Tap your Flex to see your progress. When you reach your goal, Flex will celebrate by buzzing and flashing its lights.
Your Flex tracks sleep automatically (meaning you just need to wear it to bed), but you have the option to manually start and stop sleep mode if you want your sleep log to show the time it takes you to fall asleep. When you put your Flex into sleep mode by tapping it rapidly for one or two seconds, it vibrates and shows two slowly dimming lights. Throughout the night, two blinking lights alternate. After you tap your Flex rapidly to exit manual sleep mode in the morning, it vibrates and flashes all five lights three times, then displays a spinning light pattern.
These light patterns apply to manual sleep mode only. If you let Flex automatically detect your sleep, you won't see any special light patterns.
While your Flex is charging, an indicator light will pulse to show the battery level every few seconds. Each indicator light represents progress towards the total charge. When the Flex has charged completely, all 5 indicator lights will blink.
When a silent alarm goes off, the Flex vibrates and the center light flashes.