From one side it may be based on your regular life routines – you may get up at different time regularly.
It is another aspect you may consider. You may not be able to generate enough energy for all day tasks if your sleep is not efficient. Than your body is trying to convince you to go back to bed.
In both cases after some time (20 – 30 minutes from your observations) your body may use emergency plan activating adrenal glances. This works familiar to energy drink activating reserves to be able to cope with your day needs.
Proposed on mentioned above websites solutions are not interrupting any wireless communication.