If it is a true/false question. Answer would be true. Some people never show symptoms, others show them within 7 days and for others it shows in about 30 days.
It is believed that your brain is still active for 7 minutes after heart failure/death :)
Answer: Internal influences may mean health hormones, as hormones are a key structure in how we function. An external influence could be sleep, as humans need sleep as a way to recharge, or diets as they have an effect on both hormones and physical durability