• Sleep;
  • Memory;
  • Awakenings from sleep;
  • State dependent learning


Many instances exist of significant memory loss for events during brief awakenings from sleep. The present experiment sought to determine whether such memory loss was attributable to depth of pre-awakening sleep or to length of awakening. Fourteen young adult subjects performed a standard memory task after being awakened from stage 2 or stage 4 sleep. Subjects either remained awake for 8 min or returned to sleep immediately after the learning task. Both short and long term memory were significantly worse when awakenings were made from stage 4 (deep) compared with stage 2 (light) sleep and when learning occurred immediately after being awakened. No significant effects were found when the length of the period awake after learning was lengthened. It was concluded that memory for events occurring during brief awakenings was affected by the prior stage of sleep. The effect was discussed as an example of state dependent learning.