Sympathovagal Balance in Smoking Cessation

Inclusion Criteria: * Men and Women at the age of 25 to 60 years. * Group A-D: Smokers willing to quit smoking and a FTNA-result \>5. * Group E: Never-smokers. * Signed consent after information. Exclusion Criteria: * formerly known hypersensitivity against one of the used pharmacological interventions or structurally similar drugs or against one of the ingredients. * participation in another study during this study or within 4 weeks prior to this study. * Addiction or other circumstances that prevent the patient from estimating the study and the consequences. * Pregnancy and breast-feeding * women with childbearing potential, except women that fulfill the following criteria: * post menopause * postoperative (6 weeks after both-sides ovariectomy with or without hysterectomy) * regular and correct use of prevention methods (error-rate \<1% a year), e.g. implants, depot injections, oral contraceptives, IUP) * sexual abstinence * signs that predict a possible non-compliance of the patient * exclusion because of nicorette tx: * psoriasis, dermatitis, urticaria * exclusion because of varenicline * creatinine-clearance \< 30ml/min * epilepsy * psychiatric diseases (schizophrenia, bipolar disorders, depression). * Exclusion because of methods * Diseases that increase the sympathetic level (Heart insufficiency, high blood pressure (arteria /pulmonary), obstructive sleeping apnoea, COPD) * cardiac rhythm disturbances * myocardial infarction within the last 8 weeks * polyneuropathy * diseases that come along with damages of peripheral nerves * severe or life-threatening diseases (e.g. cancer with life-expectancy \< 5 years, terminal kidney-insufficiency) * treatment with antihypertensive drugs or sympathomimetic substances (e.g.theophyllin) or smoking cessation medication (NRT, Varenicline) * Other reasons, that make a patient not suitable for the study (estimation of primary investigator)