Clarification about sleep patterns and sleep stages data

[frustra17]

Why is it that instead of a graph I sometimes end up with column bars on my sleep display?

Moderator Edit: Clarified subject

[SilviaFitbit]

@frustra17 A warm welcome to the Fitbit Community. I'll be happy to clarify your inquiry. 

You'll receive sleep stages if your Fitbit is tracking your heart rate during the night. There are few scenarios where you might see your sleep pattern (which shows your time asleep, restless, and awake) instead of sleep stages:

• If you slept in a position that prevented your device from getting a consistent heart-rate reading or wore it too loosely. For best results, wear your device higher on your wrist (about 2-3 finger widths above your wrist bone). The band should feel secure but not too tight.
• If you used the Begin Sleep Now option in the Fitbit app (instead of simply wearing your device to bed). For more information on automatic sleep tracking, see How do I track my sleep with my Fitbit device?
• If you slept for less than 3 hours.
• If your device’s battery is critically low.

Learn more about it by checking this article. 

I'll be around if you have any additional questions.