Why does stress impact on sleep?

Charlotte - Stress is a really natural response that our bodies have to a perceived threat, but it can become a problem when it disrupts your wellbeing. It can really affect your mental and physical health and that includes sleep as well, because it really affects all systems in the body, like hormones, neurotransmitters, your muscle tension, your breathing. And this is actually a really common problem. One in four adults, for example, in the US, say that they're so stressed on most days that they can't function. Something that can be helpful for people is to identify sources of stress. Is it something psychological or something physical? Is it acute or is it chronic? Like a long-term situation in your life that's really stressful? Or is it something perhaps in the environment, like pollution, poverty. Or internal, because often I find that a common recommendation is for people to make changes to their lifestyles but there is also the stress that we can't just meditate or exercise away that need more systemic solutions.