This system is the opposite of the sympathetic. It gets activated in the second stage of the stress response, the Resistance Phase. This system governs what is called rest-and-digest mode, and it strives to restore homeostasis in the body. When the parasympathetic system kicks in, it tries to recover the body from the damaging effects of the stress. The stronger the influence of the stress and the longer it lasted, the bigger the effort parasympathetic systems needs to do and longer to take to recover the body entirely.
When the next stressors come in during this restoration, the sympathetic system takes over before your body is fully ready to handle more stress. This is when additional cortisol puts you in the state of chronic stress and can eventually lead to exhaustion phase. You should give your body enough time to restore and recover to prevent this situation. Because the amount of stress we experience daily is enormous, adequate rest should be a regular part of your life – proper sleep, nutrition, breathing and mental rest (mindfulness and meditation) are a perfect restoration.