Sleep is a vital process that impacts biological functions such as cell renewal, bone regeneration,
and immune system support. Disrupted sleep can interrupt erythropoiesis, leading
to fewer red blood cells, reduced haemoglobin concentration, and decreased haematocrit levels,
potentially contributing to haematological disorders. This is particularly concerning for shift workers
for example firefighters. While previous studies have explored sleep’s adverse effects on various
professions, research specific to firefighters is limited. This study investigates the relationship between
sleep quality and haematological parameters among firefighters in Northeast Portugal. From a
sample of 201 firefighters, variations in red blood cells, haemoglobin, and haematocrit values were
linked to sleep quality. The study utilised non-parametric tests (Wilcoxon-Mann-Whitney, Spearman’s
correlation) to explore the connection between sleep quality and haematological profile. The
impact of covariates on haematological parameters was assessed using non-parametric ANCOVA
(Quade’s). A multiple regression analysis was employed to further understand how sleep quality
and various confounding variables impact haematological levels. Findings suggest a negative
link between sleep quality and haematological levels, meaning that as sleep quality deteriorates,
there is a tendency for haematological levels to decrease, as indicated by Spearman’s correlation
(rRBC = −0.157, pRBC = 0.026; rHb = −0.158, pHb = 0.025; rHCT = −0.175, pHCT = 0.013). As observed
in scientific literature, the correlation found suggests a possible inhibition of erythropoiesis,
the process responsible for red blood cell production. Despite firefighters presenting a haematological
profile within the reference range (RBC: 5.1 × 106/mm3 (SD ± 0.4), Hb: 15.6 g/dL (SD ± 1.3), 47%
(SD ± 1.0), there is already an observable trend towards lower levels. The analysis of co-variables did
not reveal a significant impact of sleep quality on haematological levels. In conclusion, this study
underscores the importance of sleep quality in determining haematological parameters among firefighters.
Future research should investigate the underlying mechanisms and long-term implications
of poor sleep quality on firefighter health. Exploring interventions to enhance sleep quality is vital
for evidence-based strategies promoting firefighter well-being.
