The injury actually comes with that first step out of bed. When you are sleeping, your foot relaxes and rests in a ‘plantarflexed’, or downward position. This position releases tension on the plantar fascia, a large ligament that spans from your heel to the ball of your foot. Over a good night’s rest, this ligament shortens, and with your first step out of bed yanks at the insertion on your heel. If you have ever had a tendon or ligament injury, you can appreciate how this can cause excruciating pain. This acute injury leads to inflammation and pain at the heel.
The phrase post-static dyskinesia is just a medical term referring to pain that occurs after rest. While it can occur throughout your body, it is most often associated with heel pain. You may be wondering why in the world this would happen to you first thing in the morning? You have just been sleeping, and barring a sleep-walking incident, could not have injured your foot.