Maybe start with a doctor or therapist? People have been doing this for a long time, and 40 hours a week really is not a long enough work week to justify having zero social interactions outside of work.
If you're struggling, perhaps it is a sign of chronic fatigue or poor sleep.
With what time? Or, rather, with what brain/blood glucose? Working 40 hour weeks leaves me with limited faculties during my comparatively brief evenings.