Don't let it become urgent. Act on emails if you need to, and delete the rest; do all the homework you intend to do, right away, so you can relax on the next ride to school.
Set the right expectations — most importantly, long response times. Don't feel wrong about saying no to that which is not contributing. Then, be deliberate in device use, so that they do not create a wrong sense of urgency, for example by alerting you to every message.
Breathe. Urgency is not necessary, and you are only as busy as you let yourself be.