12. Peppermint, cinnamon, rosemary![](https://s41998.pcdn.co/wp-content/uploads/2016/11/Rosemary-prevents-brain-aging-with-essential-oil.jpg.optimal.jpg)
These are all quite potent essential oils, so don’t go pouring them into your diffuser willy nilly! This heady combination will help you to attain better mental clarity and focus — great if you need to get some work done or have an assignment due. Two drops of peppermint, two drops of cinnamon and one drop of rosemary should do the trick.