Inclusion Criteria:  Non-SAOS Group :  Men or women aged 18 to 70 Subject without any OSAS Subject with Body Mass Index < 30 kg/m2 Subject who has given their free and informed consent in writing Subject affiliated to the French social security system (or equivalent)  SAOS Group :  Men or women aged 18 to 70 Subject with OSAS (Apnea-hypopnea index > 30/hour) Patient with CPAP indication and untreated at baseline Subject with Body Mass Index < 30 kg/m2 Effective contraception for women of childbearing age (progestational or estrogen-progestin hormonal contraceptives (pill, ring, transdermal patch), intrauterine devices or definitive sterilization) Subject who has given their free and informed consent in writing Subject affiliated to the French social security system (or equivalent)  Exclusion Criteria:  Patient with resistant hypertension (PA ≥ 140/90 mmHg despite taking at least 3 drugs of different therapeutic classes at near maximal dose, including a diuretic) Infection, progressive neoplasia, unstable cardiovascular pathologies, metabolic or intestinal pathologies Taking of pre/probiotics and/or antibiotics in the 6 months prior to inclusion Major sleepiness in at-risk populations for whom the introduction of treatment by CPAP equipment is mandatory and rapid (truck drivers, crane operators ...) according to the investigator Patient with major desaturations during its polysomnographic diagnostic recording (≥ 2h with O2 saturation <90% on total sleep time) Patient with high daytime sleepiness (Epworth score > 15) Contraindication to the implementation of a CPAP treatment for the SAOS group Contraindication to perform a subcutaneous biopsy (subject with hypersensitivity to a known local anaesthetic, abdominal skin lesion ...) Drastic diet (vegetarian, vegan, pescetarian), food allergies Subject referred to in Articles L1121-5 to L1121-8 of the CSP (pregnant woman, parturient, mother who is breast-feeding, person deprived of liberty by judicial or administrative decision, legally protected person) Subject being in an exclusion period of another study or ongoing participation in a drug study Patient likely, in the opinion of the investigator, not to be cooperative or respectful of the obligations inherent to participation in the study