i'm not a doctor, but imo: yes, blame depression and hormones
periods can sometimes drain energy.
other 'possible' causes:
- too much fruit, or foods with sugar (it makes you sleepy)
*edit: apples actually boost energy, try to stay away from fruit like pineapple and watermelon (very high in sugar).
- too much carbs (even if whole grain, it still makes you sleepy)
- incorporating more protein in your diet (it boosts energy)
- incorporating more 'dark' chocolate (rich in antioxidants, which also boosts energy)
- other forms of exercise (it's not good to do the same thing)