Erratum to “Withdrawal notice to the effectiveness of diaphragmatic breathing relaxation training for improving sleep quality among nursing staff during the COVID-19 outbreak: a before and after study” [Sleep Medicine X (2) (2020) 100026]

The Publisher regrets that this article is an accidental duplication, at the publisher's end, of an article that has already been published in Sleep Medicine 10 1016/j sleep 2020 12 003 The duplicate article has therefore been withdrawn The full Elsevier Policy on Article Withdrawal can be found at https://www elsevier com/about/our-business/policies/article-withdrawal