Efficacy of Closed-loop Ventilation to Reduced Sleep Disorders

Inclusion Criteria: * patient under invasive mechanical ventilation since at least 6 hours and for expected at least 48 hours duration, including a continuous period of 24h, from 2 p.m. to 2 p.m. the next day. * Age \> 18 years * Body Mass Index \< 40 * informed consent signed by the family Exclusion Criteria: * patient requiring neuo-muscular blocking agent or deep sedation enough to abolish spontaneous ventilatory effort * patient with encephalopathy regardless of origin * Patient with Glasgow coma scale score \< 8 * Patient abusing of drug or alcohol * patient with a contraindication for placement of a nasogastric tube such that sufferers of esophageal or gastric ulcer, tumors, diverticulitis or bleeding varices or patients with sinusitis epistaxis or having recently been operated on the nose or pharynx * Patient with bleeding disorders * Patient with unstable respiratory situation as defined by a arterial oxygen partial pressure and inspired oxygen fraction ratio (PaO2/FiO2) \< 100 mmHg with positive end expiratory pressure (PEEP) \> 12 cmH2O * Patient with unstable hemodynamic situation as defined by Systolic Blood Pressure (SBP) \< 75 mmHg despite a therapeutic optimization * Inclusion in another research protocol submitted to consent