The same per-item breakdown, run for all five drivers in the file. If a flat profile were evidence against a mechanism, sleep — 8× stronger, with an obvious mechanism — ought to look different. It does not.

driver	mean r	sd	spread ÷ size	top-5 share	strongest item
screen time	+0.0799	0.0174	0.218	30.0%	3
sleep quality	+0.2247	0.0419	0.187	28.5%	19
hours slept	−0.1537	0.0330	0.215	30.4%	19
weekend midsleep	+0.0878	0.0321	0.366	36.1%	19
social jetlag	+0.0421	0.0245	0.581	44.7%	19

spread ÷ size is the standard deviation of the 21 correlations divided by their mean, so drivers of very different strength can be compared. Screen time 0.218, sleep quality 0.187. Social jetlag, the weakest driver in the file, is the least uniform of the five — the opposite of what the discarded reading would predict.

the one item that does stand out

Item 19 is the strongest correlate of every sleep measure here, all four of them. That is a real pattern rather than an artefact of one noisy column. The source ships the items unlabelled, so what it asks is not something I can tell you.

driver	strongest	its r	weakest
screen time	item 3	+0.1133	item 6
sleep quality	item 19	+0.2844	item 21
hours slept	item 19	−0.2197	item 21
weekend midsleep	item 19	+0.1477	item 13
social jetlag	item 19	+0.0866	item 13