PROBLEM TO BE SOLVED: To provide an awakening device, a sheet having the awakening device, and a method of judging a degree of awakening with low processing load for judging awakening and with high accuracy of judging the degree of awakening.SOLUTION: An awakening device comprises: a heart rate sensor for acquiring a cardiac potential signal of a person； a calculation part for calculating the cardiac potential signal acquired from the heart rate sensor； a waveform generation part for forming a RRI (R-R Interval) waveform with regard to an electrocardiographic waveform in the cardiac potential signal； and a judgement part for judging a degree of awakening of the person on the basis of the cardiac potential signal. Among the RRI waveforms, with a point of time when a value of a RRI gets lower than a value of an immediately preceding RRI as an anchor, the calculation part duplicates the RRI waveforms for a number of the anchors, moves a time axis of the duplicated RRI waveform so as to be the same phase as the anchor point of the RRI waveform, and calculates a PRSA (Phase-Rectified Signal Averaging) signal defined as an average value of the RRI for each time axis. The judgement part judges the degree of awakening of the person corresponding to the value of the RRI and the PRSA signal.【課題】覚醒判定のための処理の負荷が低く、覚醒度判定の正確性が高い覚醒装置、当該覚醒装置を備えるシート、及び覚醒度判定方法を提供する。【解決手段】覚醒装置は、人の心電位信号を取得する心拍センサと、心拍センサから得られた心電位信号を演算する演算部と、心電位信号に係る心電波形についてのＲＲＩ波形を生成する波形生成部と、心電位信号に基づいて人の覚醒状態を判定する判定部と、を備える。演算部は、ＲＲＩ波形のうち、直前のＲＲＩの値よりもＲＲＩの値が低くなる時点をアンカーとして、アンカーの数だけＲＲＩ波形を複製し、ＲＲＩ波形のアンカー時点が同位相となるように複製したＲＲＩ波形の時間軸を移動して、各時間軸におけるＲＲＩの平均値として定義されるＰＲＳＡ信号を算出する。判定部は、ＲＲＩの値とＰＲＳＡ信号の値とに応じて、人の覚醒状態を判定する。【選択図】図２
