Did you know that one of the "coolest" essential oils available is peppermint? Not only will it help alleviate headaches when placed on the temples, it will also help to clear that feeling of brain fog that may sometimes appear out of nowhere. Place a few drops of peppermint on the back of your neck and it will help to cool you down in the middle of a pesky hotflash. Peppermint essential oil is the "coolest".