This study aimed to investigate the relationship between sleep disorders and lymphocyte subsets and cytokines in patients with lung cancer undergoing radiotherapy, and to establish a theoretical foundation for predicting sleep disorders and preventing interventions in radiotherapy in lung cancer patients. Ninety-two patients with lung cancer requiring radiotherapy were selected as the study subjects. The patients' demographic data and disease-related conditions were investigated. Their quality of sleep was measured before radiotherapy, after two and four weeks of radiotherapy, and at the end of radiotherapy. According to the Pittsburgh Sleep Quality Index Number Table (PSQI), patients with PSQI score> 7 points were put into a sleep disorder group, and patients with PSQI score 0-7 were put into a normal sleep group. Lymphocyte subsets were enumerated and cytokine levels (IL-6, IL-1b) were measured during these four periods. The difference in sleep disorders at four weeks between patients with or without synchronous chemotherapy was statistically significant (P less than 0.05). The levels of lymphocyte subsets in the sleep disorder group and the control sleep group showed no difference in the index of lymphocyte subsets before radiotherapy. In the sleep disorder group, CD4+ cells were lower after two weeks of radiotherapy (P less than 0.05). After four weeks of radiotherapy, CD3+, CD4+, and CD16+56+ subsets were lower (P less than 0.05). At the end of radiotherapy, there was no difference in each index. There was no significant difference in IL-6 levels between the two groups before radiotherapy, after two weeks, or after four weeks (P greater than 0.05). At the end of radiotherapy, IL-6 levels in the sleep disorder group were higher than those in the control sleep group (P less than 0.05). There was no significant difference in IL-1b between the two groups (P greater than 0.05). In conclusion, monitoring of T-lymphocyte subsets and IL-6 levels in patients is enhanced during radiotherapy. Clinically effective programs of radiotherapy for lung cancer improve the body's immune status.