Not a DOI

The resolution service at https://doi.org resolves DOIs. You have attempted to resolve core/journals/the-british-journal-of-psychiatry/article/daytoday-associations-between-subjective-sleep-and-affect-in-regard-to-future-depressionin-a-female-populationbased-sample/DCFF5347D39E15FB14831A163A039D44, which is not a DOI.

core/journals/the-british-journal-of-psychiatry/article/daytoday-associations-between-subjective-sleep-and-affect-in-regard-to-future-depressionin-a-female-populationbased-sample/DCFF5347D39E15FB14831A163A039D44 may be a Handle (DOIs are a special sort of Handle). If core/journals/the-british-journal-of-psychiatry/article/daytoday-associations-between-subjective-sleep-and-affect-in-regard-to-future-depressionin-a-female-populationbased-sample/DCFF5347D39E15FB14831A163A039D44 is a valid Handle you should be able to resolve it at https://hdl.handle.net.