Question: Why do we feel tired?

Petrina Lau answered on 13 Nov 2018:

Hi there, feeling tired can be have psychological causes, physical causes and/or lifestyle causes. Psychological, stress and strong emotions make keep you up. You may feel tired after intense exercise. Or living in a noise area. When one has been awake for long, his/her brain activity pattern starts to change, a slow oscillation at delta range starts to dominate the brain activity spectrum, that’s what scientist called building up sleep pressure. After sleep enough, this delta frequency brain activity returns to “normal”. 🙂