We are all guilty of falling down a midnight rabbit hole of depressing news or flawless social media feeds. But what does it actually do to our nervous systems? Quite a lot, actually. Every distressing headline or too-perfect photo tells your body there is danger nearby, even though you are just lying safely in bed. It reacts the way it always has: heart rate up, breathing shallower, stress hormones flooding in, ready to fight or run from something that isn't actually there. Normally, that response fades once the threat passes, but doomscrolling keeps your system on high alert. Do this late at night and your body loses its critical window to wind down for sleep, leaving you feeling wired and exhausted at once. 

While many assume late-night stress simply swaps out natural sleep hormones for alertness chemicals, Dr Shaunak Ajinkya, consultant psychiatrist, Kokilaben Dhirubhai Ambani Hospital, Mumbai, points out that the underlying physiological reality is far more nuanced, "It is important to clarify that melatonin and cortisol do not literally replace one another. Melatonin signals the body that it is time to wind down and sleep, while cortisol is part of the body's stress and alertness system. When we experience stress, anxiety or intense stimulation close to bedtime, the brain can remain in a state of heightened arousal when it should be transitioning into rest.”