Cortisol

Many of us know the state of being “wired but tired” – feeling physically exhausted yet mentally unable to switch off. But the brain does not simply fall asleep because the body is fatigued – and part of the reason lies in the biology of survival.

If you deal with waves of daytime drowsiness, you might be among the estimated 33% of the population suffering from excessive daytime sleepiness. In the largest study of its kind, scientists have uncovered the condition's unique biological fingerprint.

For the first time, researchers have shown how staying hydrated influences how our bodies react, hormonally, to stress, keeping cortisol in check and in turn lowering the risk of serious health conditions including heart disease, obesity and diabetes.

For the first time, scientists have uncovered a distinct biological process triggered in those who suffer from high levels of Monday anxiety, resulting in chronic stress. And it can lead to serious health problems if it's left unmanaged.

You already know when you are feeling highly stressed, but low-grade background stress is harder to detect. A new dental flosser from researchers at Tufts University aims to make it easier by monitoring the chemistry of your saliva.