An effect similar to drift is observable at tennis, golf, base-ball and cricket; but this effect is explainable by the inequality of pressure due to a vortex of air carried along by the rotating ball, and the deviation is in the opposite direction of the drift observed in artillery practice, so artillerists are still awaiting theory and crucial experiment.
People may feel tired for no explainable reason, such as the sensation of having a general lack of sleep.
These situations are sometimes explainable with thorough medical testing; both women and men can be infertile for a variety of reasons.
In the end, most established paranormal research groups do an excellent job separating explainable phenomenon from authentic paranormal activity.
If your bruise worsens, begins to swell, does not fade or begin to fade within a week, occurs for no clear reason or occurs frequently for no explainable reason, you are advised to seek medical attention.