The natural forces of the lunar cycle and seasonal solstice variation on the water surfaces have been studied extensively but not on patients with fluid problems such as heart failure (HF). This retrospective review investigates these temporal effects on admission rates of patients with heart failure and length of stay. In this study, we try to answer the following questions: Do moon cycles (full moon vs new moon) significantly affect the number of patients admitted? and Do moon cycles significantly affect the patient's hospital length of stay (LOS?). All patients with HF exacerbation admission between January 1, 2016 to December 31, 2019, were filtered according to admission date based on the lunar calendar. Patients admitted on the day of, the day before, and the day after a new and full moon were included. Question 1, Poisson regression models were employed. The overdispersion obtained from the AER package was 1.63. All analyses were performed using R (R Core Team). A total of 758 patients were admitted during lunar cycles, 50.1% (N = 380) were admitted during the new moon and 49.4% (N = 378) during the full moon. The mean age is 78.4 (SD 7.2), the mean BMI is 28.8 (SD 6.7), and the mean LOS is 5.6 (SD 3.4) with no significant differences in patients admitted during both of the moon cycles. The seasons variable showed statistically significant coefficients, with the summer season (S2) having the highest impact (coefficient 0.85, P = .002). Some interaction between Moon-Cycle, summer season, and BMI influenced patient admissions during lunar cycles (coefficient = 0.49 P ≤ .002). This study showed that the moon cycle may impact patients with HF during the summer season only. Prospective studies are needed on a national level to investigate further the impact of the moon cycle on HF patients. This will help improve patient outcomes and pathogenesis, and there is excellent potential for reducing medical costs.