According to recent evidence, the hippocampus kicks off the first steps of memory consolidation seconds after the first exposure with the target content. However, this process is believed to take days to complete. The breathing rhythm is also shown to impose an independent oscillation in the hippocampus. If these oscillations can be used to improve the first memory registration steps is unclear. This study used a Mnemonic Similarity Task, a behavioral test to probe pattern separation as an index for a highly detailed memory in humans. Pattern separation has been employed before for testing the effects of neurogenesis improvements in the hippocampal DG. In the present study, we utilized this paradigm to investigate if hippocampal stimulation through slow breathing can improve detailed memory in the short term. The two-minute slow breathing interventions of 6 bpm could not improve the pattern separation in a two-day between-subject design for the first three distancing bins and reduced the performance significantly in the fourth bin (D4) with 48-70 trials between the pairs. The control group of each day took two-minute sessions of 15 bpm normal breathing practices. The healthy young adult participants (18-29 years old) were most likely already at a saturated performance, and an intervention could only take effect in the presence of a disadvantage in this age group which is provided in the fourth distancing bin. A reduced pattern separation performance in D4 might be due to an unintentional activation of a second circuitry enervating into the locus coeruleus (LC) that downregulated the brain at the time of encoding.