Sleep disturbance and daytime sleepiness in adults with iron deficiency anemia in primary care: associations with iron status and verbal fluency

Sleep-related symptoms are common but may remain under-recognized during routine primary care consultations. Iron deficiency anemia is frequently managed in primary care and may be accompanied by daytime sleepiness, non-restorative sleep, and functional cognitive complaints. This study aimed to examine the associations of routinely available iron-status markers with subjective night-sleep disturbance and daytime sleepiness among adults with laboratory-confirmed iron deficiency anemia attending a primary care clinic. As secondary exploratory outcomes, self-reported cognitive flexibility and verbal fluency performance were also evaluated. This single-center cross-sectional study included 190 adults aged 18–65 years with laboratory-confirmed iron deficiency anemia who attended a family medicine outpatient clinic. Participants completed the SCOPA Sleep Scale, Cognitive Flexibility Inventory, phonemic verbal fluency tasks using the Turkish letters K/A/S, and semantic category fluency tasks. Hemoglobin, serum iron, ferritin, and other hematological parameters were obtained from routine laboratory records. Correlation analyses and exploratory adjusted linear regression models were used to evaluate associations between iron-status markers and sleep or functional cognitive outcomes. Multivariable models were adjusted for age, sex, education level, body mass index, smoking status, alcohol use, and weekly meat/protein intake. The mean age was 38.83 ± 12.07 years, and 85.3% of participants were female. Hemoglobin was negatively correlated with daytime sleepiness, while serum iron was inversely correlated with both night-sleep disturbance and daytime sleepiness. Ferritin showed positive correlations with phonemic verbal fluency scores. In exploratory adjusted regression analyses, serum iron remained inversely associated with night-sleep disturbance. Hemoglobin and ferritin remained positively associated with phonemic fluency total, whereas adjusted associations with self-reported cognitive flexibility and semantic fluency were not statistically significant. Among adults with iron deficiency anemia in a primary care setting, lower values of selected iron-status markers were associated with greater subjective sleep-related symptom burden and lower performance in selected verbal fluency measures. These findings support the potential value of brief sleep-health assessment during routine primary care evaluation of adults with iron deficiency anemia. However, the cross-sectional design, absence of a control group without iron deficiency anemia, limited cognitive assessment, lack of inflammatory markers, and exploratory multiple testing preclude causal interpretation.