Scientists who discovered the association also found evidence of the causal link between longer sleep and illness.
Researchers who compared data on hundreds of thousands of women found that patients with a built-in early preference were 40 to 48 percent less likely to be at risk of breast cancer.
Part of the analysis also showed that women who slept longer than recommended seven to eight o'clock in the night increased their chances of diagnosing by 20% for each additional hour they were falling asleep.
The study highlighted that individuals who were genetically predisposed were either "larki" or "owls".
Larks tend to get up and go to sleep early, while owls have body clocks that lead them to the morning of drowsiness in the morning and the most energetic evening.
Scientific Head of Dr. Rebecca Richmond, of Bristol University, said: "Using genetic variants associated with people's preference for morning or evening times, sleeping and insomnia … we examine whether these sleep patterns have a causal contribution to breast cancer risk.
"We'd like to do more work to find out the mechanisms on which these results are based, as the estimates are based on questions relating to morning or evening preference rather than whether people are rising sooner or later.
"In other words, it may not happen that changing your habits changes your risk of breast cancer, it may be more complicated than that.
"However, the findings of the protective effect of early preferences on breast cancer risk in our study are consistent with previous research that highlights the role of night shift work and exposure to light at night as risk factors for breast cancer."
The findings were presented at the NCRI (National Cancer Research Institute) conference in Glasgow in 2018.
The women who participated in the study included 180,215 participants of the UK Biobank project, which holds data on medical research at 500,000 individuals.