The sympathetic nervous system was thought to have evolved with jawed vertebrates. But lampreys—jawless, parasitic fish that suck out the blood of their hosts—have a simple one, per recent research.

Researchers have created a digital topographical map of the cardiac sympathetic neural network, the region that controls the body's heart rate and its 'fight-or-flight' response. They hope this map ...

Why the "rest and digest" system is crucial for well-being Medically reviewed by Steven Gans, MD Stress seriously affects your body, mind, and ability to feel like yourself. While you might feel like ...

The brain sleeps best when it feels safe, relaxed, and satisfied — exactly the state good sex produces. But women also experience post-sex sleepiness, especially after orgasm. We don’t sleep after ...