1The first day back is worse than the weeks before it, not better. Plan for that spike rather than letting it take you by surprise.
Anxiety climbs as the return gets close and peaks somewhere near the doorway, then it comes down, but only for someone who stays long enough to find that out. Put the supports in place before the date arrives: who meets them, where they can go if it gets too much, what the first hour actually asks. Deciding all of that on the morning, in tears, rarely goes well.
Islamic evidence
We shall certainly test you with fear and hunger, and loss of property, lives, and crops. But give good news to those who are steadfast (Quran 2:155). The fear is named in advance here, which is a kind of preparation in itself.
“We shall certainly test you with fear and hunger, and loss of property, lives, and crops. But [Prophet], give good news to those who are steadfast”
Qur'an 2:155
Psychological evidence
Reviews of exposure therapy written from an inhibitory learning view argue that what makes approaching a feared thing work is the gap between what you expected and what happened, and that quiet forms of avoidance blunt exactly that gap. These are theoretical reviews drawing laboratory and clinical findings together rather than a trial of going back to school. Read at that level, they explain why a long absence leaves the frightening prediction untouched and loud.
Craske MG, Treanor M, Conway CC, Zbozinek T, Vervliet B. (2014). Behaviour research and therapy · doi
Review detail
Why it works. A fear that has gone months without being tested has had nothing to shrink it, so it turns up at full size.