Myth: Cortisol is a stress hormone, serotonin a happiness hormone

Hormones don't just have one specific psychological purpose, and all the chemicals work together in your mind.

• Cortisol boosts the amount of glucose in your bloodstream for a quick burst of energy, such as before you exercise or wake up in the morning, not just when you are stressed.
• Serotonin has many functions. It regulates how much fat is made and helps keep track of your energy. It also helps other neurons pass on information as they create your thoughts, feelings and actions.