Every patient receiving invasive mechanical ventilation needs an adequate analgesia and sedation. Based on validated scores, the individual titration of sedation and analgesia aims to maximise patient comfort and optimise patient-ventilator synchrony. By regular re-evaluation (e. g., three times a day) of the drug doses a day-night-time rhythm, with a deeper sedation during the night, can be achieved. It is important to know that the recommendations concerning the drug doses are often based on a single application, which does not reflect the real elimination kinetics of a continuous drug delivery. This may significantly change in critically ill patients. Using a modern concept of analgo-sedation, it is often possible to establish spontaneous breathing during mechanical ventilation and to promote successful early weaning of the patient.