As Neils Bohr showed, it is possible for electrons to move between energy levels. Light contains energy. If a photon of light strikes an atom, it is possible for the energy in the light ray to be transferred to one of the low energy electrons moving around the atomic center.
Spotting before a period is due â reasons for spotting before a period can be implantation, from a cyst or a short luteal phase and impaired egg quality. Spotting in between cycles â this is a difficult term to answer but often means your cycles are growing shorter; often with perimenopause.
Certain problems related to pregnancy can cause spotting. Also note that some women experience spotting during ovulation, so if you only notice the bleeding mid-cycle, this could be the cause. If the spotting does not improve with a lighter exercise regimen, I would recommend seeing a doctor for a full evaluation.