Do you know what your hormone levels are? Should you? Your body is home to more than 50 hormones — chemical messengers that compose the endocrine system — and hormonal changes may reflect any number of medical conditions. For example, low levels of the pancreatic hormone insulin may indicate diabetes , while high levels of the stress hormone cortisol can play a role in obesity . But some hormones such as melatonin , which is important for sleep, naturally fluctuate throughout the day. Other