Abstract: https://doi.org/10.5664/jcsm.9554 LETTERS TO THE EDITOR What if melatonin could help patients with severe COVID-19?

Miguel Angel S
anchez-Gonz
alez, MD, PhD1,2; Ignacio Mah
ıllo-Fern
andez, PhD3; Felipe Villar-Alvarez, MD, PhD4; Luc
ıa Llanos, MD, PhD5 Psychiatry Department, Fundaci
on Jim
enez D
ıaz University Hospital, Health Research Institute (IIS-FJD, UAM), Madrid, Spain; 2Department of Anatomy, Histology, and Neuroscience, School of Medicine, Universidad Aut
onoma de Madrid, Madrid, Spain; 3Biostatistics Unit, Fundaci
on Jim
enez D
ıaz University Hospital, Health Research Institute (IIS-FJD, UAM), Madrid, Spain; 4Pulmonology Department, Fundaci
on Jim
enez D
ıaz University Hospital, Health Research Institute (IIS-FJD, UAM), CIBERES, Universidad Aut
onoma de Madrid, Madrid, Spain; 5Clinical Research Unit, Fundaci
on Jim
enez D
ıaz University Hospital, Health Research Institute (IIS-FJD, UAM), Madrid, Spain 1 Copyright 2022 American Academy of Sleep Medicine. All rights reserved. In March 2020, a protocol recommending the prescription of melatonin, among other sleep- and biorhythms-promoting measures, to hospitalized patients with coronavirus disease 2019 (COVID-19) with sleep problems or delirium was sent from the consultationliaison psychiatrist to the medical staff of the Fundaci
on Jim
enez D
ıaz University Hospital (FJDUH) in Madrid, Spain. Several authors have suggested a potential benefit of melatonin use in COVID-19.1–4 In addition to its circadian function, melatonin is thought to have several health-promoting properties, including immune response modulation and anti-inflammatory and antioxidant properties.5 We here report a retrospective analysis showing an association of melatonin with survival in a sample of 2,463 Table 1—Unmatched and matched groups of melatonin and non-melatonin patient characteristics, and comparison of mortality and hospital stay between matched groups. Variable Demographics and clinical history Agea Female CVD DM Hypertension Lung disease Dyslipidemia Smoking habit Treatment-related ICU/IRCU stay Dexamethasone Tocilizumab Cyclosporine Methylprednisolone Anakinra Nasal cannula oxygen High-flow oxygen Clinical evolution Hospital stay, d Mortality Melatonin (n = 224) Unmatched Comparisons Matched Comparisons Non-Melatonin (n = 1,952) P Value Non-Melatonin (n = 224) P Value Effectb (95% CI) 69.0 (22.5) 96 (42.9%) 61 (27.2%) 53 (23.7%) 113 (50.4%) 54 (24.1%) 95 (42.4%) 14 (6.2%) 74.0 (28.0) 917 (47.0%) 594 (30.4%) 378 (19.4%) 1,052 (53.9%) 443 (22.7%) 738 (37.8%) 152 (7.8%) .054 .271 .362 .150 .363 .694 .204 .492 70.0 (25.0) 97 (43.3%) 62 (27.7%) 39 (17.4%) 112 (50.0%) 58 (25.9%) 80 (35.7%) 20 (8.9%) .982 > .99 > .99 .128 > .99 .743 .175 .372 — — — — — — — — 53 (23.7%) 42 (18.8%) 67 (29.9%) 138 (61.6%) 183 (81.7%) 11 (4.9%) 184 (82.1%) 34 (15.2%) 112 (5.7%) 109 (5.6%) 177 (9.1%) 677 (34.7%) 1,167 (59.8%) 13 (0.7%) 1,272 (65.2%) 82 (4.2%) <.001 <.001 <.001 <.001 <.001 <.001 <.001 <.001 43 (19.2%) 32 (14.3%) 71 (31.7%) 145 (64.7%) 192 (85.7%) 7 (3.1%) 171 (76.3%) 26 (11.6%) .300 .252 .759 .557 .306 .470 .162 .332 — — — — — — — — 13.7 (23.1) 24 (10.7%) 5.9 (6.7) 340 (17.4%) <.001 .014 8.9 (10.9) 53 (23.7%) <.001 <.001 4.8 (2.3–6.2) 0.39 (0.23–0.65) a Expressed as median (interquartile range). bMedian differences for hospital stay and odds ratio..