The invention relates to a method and device for contactless monitoring and evaluation of sleep states of a user. The invention comprises a seamless continuous evaluation of cardiac activity variability and uses these data as an input for evaluation and quantitative assessment of sympathetic and parasympathetic activity of autonomic nervous system, which are reliable markers of physiological condition of a user. The device is embedded within two thin mattress pad layers, eliminating any direct contact between electrodes and a user's body. The invention enables remote monitoring and evaluation of sleep states without involvement of trained professionals.