Regulation of hormone levels
When Nicotine is used on a daily basis it stabilizes the Adrenal hormones by acting on the Hypothalamus, which affects the pituitaries release of regulating hormones and increases GH release. This keeps various hormone levels stable during times of depression, or stress. That is why a smoker can have a cigarette in the morning to wake up and one at night to help relax.
When you stop using nicotine your whole endocrine system gets f_cked up. Your cortisone, and adrenaline levels take a nosedive until your natural hormone regulation takes control again. Fortunately nicotine does not seen to have a negative effect on GH release upon cessation.
Getting your natural hormone levels back in order takes about two weeks. As body builders we can use this to our advantage. When you stop a cycle you can start using nicotine. This will quickly reduce the high cortisone levels to a normal level. After coming off nicotine you can start a new cycle and take advantage of the low cortisone levels for the first two weeks