Often we can get used to stimulation. But sometimes we think we have and aren’t being bothered, but suddenly feel exhausted and realize why: We have been putting up with something at a conscious level while it was actually wearing us down. Even a moderate and familiar stimulation, like a day at work, can cause an HSP [highly sensitive person] to need quiet by evening. At that point, one more ‘small’ stimulation can be the last straw.
Elaine Aron, The Highly Sensitive Person