Predicting menstrual cycles can be challenging, but it’s possible to predict when your period will start by paying attention to certain factors. Diet is important: eating a healthy, balanced diet can help regulate hormones and promote regular periods. Stress, too, affects the menstrual cycle; high levels can disrupt hormone balance and cause irregular or missed periods. Exercise helps maintain regular periods by regulating hormones and reducing stress. Hair growth may give some indication of an individual’s overall health, but it can’t reliably predict when one’s period will start – there are many other factors at play.