Cramming for a test? Trying to get more done than you have time to do? Stress is a feeling we all experience when we are challenged or overwhelmed. But more than just an emotion, stress is a hardwired physical response that travels throughout your entire body. In the short term, stress can be advantageous, but when activated too often or too long, your primitive fight or flight stress response not only changes your brain but also damages many of the other organs and cells throughout your body. Your adrenal gland releases the stress hormones cortisol, epinephrine, also known as adrenaline, and norepinephrine. As these hormones travel through your blood stream, they easily reach your blood vessels and heart. Adrenaline causes your heart to beat faster and raises your blood pressure, over time causing hypertension. Cortisol can also cause the endothelium, or inner lining of blood vessels, to not function normally. Scientists now know that this is an early step in triggering the process of atherosclerosis or cholesterol plaque build up in your arteries. Together, these changes increase your chances of a heart attack or stroke. When your brain senses stress, it activates your autonomic nervous system. Through this network of nerve connections, your big brain communicates stress to your enteric, or intestinal nervous system. Besides causing butterflies in your stomach, this brain-gut connection can disturb the natural rhythmic contractions that move food through your gut, leading to irritable bowel syndrome, and can increase your gut sensitivity to acid, making you more likely to feel heartburn. Via the gut's nervous system, stress can also change the composition and function of your gut bacteria, which may affect your digestive and overall health. Speaking of digestion, does chronic stress affect your waistline? Well, yes. Cortisol can increase your appetite. It tells your body to replenish your energy stores with energy dense foods and carbs, causing you to crave comfort foods. High levels of cortisol can also cause you to put on those extra calories as visceral or deep belly fat. This type of fat doesn't just make it harder to button your pants. It is an organ that actively releases hormones and immune system chemicals called cytokines that can increase your risk of developing chronic diseases, such as heart disease and insulin resistance. Meanwhile, stress hormones affect immune cells in a variety of ways. Initially, they help prepare to fight invaders and heal after injury, but chronic stress can dampen function of some immune cells, make you more susceptible to infections, and slow the rate you heal. Want to live a long life? You may have to curb your chronic stress. That's because it has even been associated with shortened telomeres, the shoelace tip ends of chromosomes that measure a cell's age. Telomeres cap chromosomes to allow DNA to get copied every time a cell divides without damaging the cell's genetic code, and they shorten with each cell division. When telomeres become too short, a cell can no longer divide and it dies. As if all that weren't enough, chronic stress has even more ways it can sabotage your health, including acne, hair loss, sexual dysfunction, headaches, muscle tension, difficulty concentrating, fatigue, and irritability. So, what does all this mean for you? Your life will always be filled with stressful situations. But what matters to your brain and entire body is how you respond to that stress. If you can view those situations as challenges you can control and master, rather than as threats that are insurmountable, you will perform better in the short run and stay healthy in the long run.
為考試臨時抱佛腳? 想在有限時間內完成更多的事? 壓力是我們被挑戰時 或對事情應接不暇時的一種感覺 但它不僅是一種情緒而已 壓力是一種與生俱有的 全身性生理反應 短時間的壓力可能有好處 但太常發生或發生時間太長 你本能對付壓力 - 戰鬥或逃脫 - 的反應 不只是改變你的大腦 也會損傷你全身 許多其他器官及細胞 你的腎上腺會釋出多種壓力賀爾蒙 包括皮質醇、腎上腺素 -- 也就是眾所周知的 adrenalin 及去甲腎上腺素 (norepinephrine) 當這些賀爾蒙在血流運行 很容易就到達血管及心臟 腎上腺素會使心跳加速 使血壓上升,久而久之就造成高血壓 皮質醇也會導致血管內皮細胞層 (血管最內層) 不能正常運作 科學家現在暸解 這是一種引發動脈硬化 或動脈堆積膽固醇斑塊 的初始步驟 綜合這些變化,會增加 心臟病發作或中風的機會 當大腦感受到壓力 它會激活自主神經系統 透過此神經連結的網絡 大腦會傳送壓力到腸道神經系統 大腦會傳送壓力到 腸道神經系統 除了造成你忐忑不安外 這種腦 - 腸連結能擾亂 運送食物通過腸子的 自然節律性收縮 而導致激腸症候群 並且增加腸道對酸的敏感性 使你更容易有胃灼熱感 透過腸道神經系統 壓力也能改變腸道 細菌的組成及功能 從而影響你的消化及整體健康 談到消化機能, 慢性壓力會影響你的腰圍嗎? 是的 皮質醇能增加你的食慾 它會告訴身體,用高能量的食物和碳水化合物 補充你的能量庫存, 使你渴望吃舒壓食物 高濃度皮質醇能使你 因那些額外的卡路里 變成內臟或腹部深層脂肪而發胖 這種脂肪不只是使 你的褲子紐扣難以扣上而已 它還可以自動釋放賀爾蒙 及一種免疫化學物質, 叫細胞激素 (cytokines) 從而增加發生慢性疾病的風險 例如心臟病及胰島素抗性 同時,壓力賀爾蒙 以多種方式影響免疫細胞 起先,它們會協助對抗入侵者 及協助損傷後的修復 但慢性壓力會 降低一些免疫細胞的功能 使你容易受到感染, 及減緩修復的速度 想要長命百歲嗎? 你必須抑止你的慢性壓力 那是因為它與端粒變短有關 端粒位於染色體末端(狀如鞋帶尾端), 用來測量細胞的年齡 端粒覆蓋在染色體的末端 每當細胞分裂,讓 DNA 得以複製 而不損傷細胞的遺傳密碼 它們隨著每次細胞分裂而縮短 當端粒變得太短時, 細胞就無法分裂而死亡 此外 慢性壓力甚至還有更多方式 來摧毀你的健康 包括痤瘡 掉髮 性功能障礙 頭痛 肌肉緊張 專注困難 疲倦 及煩躁不安 所以,以上這些意謂著什麼? 生活總是處處充滿著壓力 但對大腦及整個身體 重要的是 你對壓力的反應如何? 假如你能把那些狀況視為 可以控制及駕馭的挑戰 而不是當作難以承受的威脅 短期來看,你會表現得比較好; 長期而言,你會活得比較健康。