Effects of habitual self-awakening on nocturnal sleep, autonomic activity prior to awakening, and subjective condition after awakening

Some people habitually wake up at a certain time every morning, in the absence of an external signal. People who are engaged in this “habitual self-awakening” reportedly feel better upon awakening and are subsequently less sleepy during the daytime. The present study examined the effects of habitual self-awakening on sleep structure and autonomic nervous system activity before awakening, and on mood after awakening. Data were analyzed from 11 university students who successfully awoke within 30 min of the target time in the self-awakening condition. These same students also participated in a forced-awakening condition. All-night sleep structure for the successful self-awakening night was not different from that observed on the forced-awakening night. However, sleep efficiency decreased, and the length of sleep stage 1 and heart rate during NREM sleep both increased during the last hour of sleep on the successful self-awakening night. Subjective morning sleepiness was reduced after the self-awakening night as compared to the forced-awakening night. These results suggest that habitual self-awakening prepares individuals for awakening during the last hour of nocturnal sleep, without significantly disturbing the sleep structure of the entire night. This process facilitates a smooth transition from sleep to wakefulness and produces positive benefits after awakening, including as waking up relatively easily and feeling less sleepy subsequent to waking up.