2.1. Study participants
This cross-sectional study was conducted on 150 patients with hematologic and non-hematologic cancers, ages 16 to 80, admitted to the internal ward of Tehran’s Imam Khomeini Hospital Complex in the fall of 2022. Initial estimates placed the sample size at 145 patients, based on a study indicating that circadian rhythm disturbances and sleep disorders were prevalent in 30-75% of cancer patients, or nearly twice the rate in the general population (25). Five additional patients were added for a total of 150 to prevent losses. Inclusion criteria were age 15 or older, a cancer diagnosis, consent to participate in the study, absence of comorbidities, and absence of intubation. Exclusion criteria were using Melatonin, sedative, and hypnotic medications, significant cognitive impairment, night-shift workers, and end-stage patients. This study was conducted per the Declaration of Helsinki and was approved by the Imam Khomeini Hospital Complex, Tehran University of Medical Science, Tehran, Iran, Ethics Committee (ethics number: IR.TUMS.IKHC.1398.28). All patients were informed of the study, and consent forms were obtained.