An apparatus equipped with means for estimating pain and nociception while awake, during general anesthesia or sedation from data including electroencephalogram (EEG), facial electromyogram (EMG), heart rate variability (HRV) by electrocardiogram (ECG) and plethysmography by impedance cardiography (ICG), the apparatus comprising the following features: (a) means for obtaining a signal containing EEG and facial EMG, said mean adapted for recording from a subjects scalp with three electrodes positioned at middle forehead, left (right) forehead and the left (right) cheek; (b) means for obtaining a three leads ECG signal and adaptations for calculating the R-R interval and the HRV from said ECG signal; (c) means for obtaining an ICG signal with four electrodes positioned at the chest of the patient; (d) means for obtaining the plethysmographic from the ICG; (e) adaptation for calculating the Fast Fourier Transform (FFT) and the Choi-Williams distributions for about 1-60 seconds of the EEG signal; (f) adaptations for calculating the frequency spectrum in about 1-10 seconds EMG signal; (g) adaptations for calculating the spectral edge frequency of the spectrum of the R-R interval of the ECG over about 2-6 minutes; (h) adaptations for calculating the Hilbert transform of the ICG signal from which the number of peaks over a certain threshold in the 1st derivative of the Hilbert phase, is estimated; (i) means adapted for combining the extracted EEG, EMG, ECG, and ICG data into a final index of nociception represented by a scale from 0 to 99, where a value of 99 represents a high probability of response to light noxious stimuli and a value of close or equal to 0 corresponds to a total block of afferent noxious stimuli, for example obtained by local anesthetic drugs. (a) means for obtaining a signal containing EEG and facial EMG, said mean adapted for recording from a subjects scalp with three electrodes positioned at middle forehead, left (right) forehead and the left (right) cheek; (b) means for obtaining a three leads ECG signal and adaptations for calculating the R-R interval and the HRV from said ECG signal; (c) means for obtaining an ICG signal with four electrodes positioned at the chest of the patient; (d) means for obtaining the plethysmographic from the ICG; (e) adaptation for calculating the Fast Fourier Transform (FFT) and the Choi-Williams distributions for about 1-60 seconds of the EEG signal; (f) adaptations for calculating the frequency spectrum in about 1-10 seconds EMG signal; (g) adaptations for calculating the spectral edge frequency of the spectrum of the R-R interval of the ECG over about 2-6 minutes; (h) adaptations for calculating the Hilbert transform of the ICG signal from which the number of peaks over a certain threshold in the 1st derivative of the Hilbert phase, is estimated; (i) means adapted for combining the extracted EEG, EMG, ECG, and ICG data into a final index of nociception represented by a scale from 0 to 99, where a value of 99 represents a high probability of response to light noxious stimuli and a value of close or equal to 0 corresponds to a total block of afferent noxious stimuli, for example obtained by local anesthetic drugs. <EOS>