„On average across countries, just over one-third (35 %) of fourth grade students […] reported that they arrive at school feeling tired ‚every day or almost every day‘.“
IEA (Hrsg.), TIMSS 2019. International Results in Mathematics and Science (2020), S. 412.
In Österreich waren es sogar 44 %. (Quelle: ibidem, Exhibit 10.5.)