English: "(A) Hypnogram of the nap. The blue arrow indicates the third instance when auditory and visual cues for lucid-dream induction were administered. We administered 24 math problems but refrained from immediately awakening this participant for a dream report due to highly fragmented REM sleep, with many stage N1 intrusions and movement arousals (indicated by red at bottom). (B) A period of wake with an LRLRLR signal (left, gray arrow in A) and a period of REM (right, red arrow in A). The math problem in this example (1 plus 2) was the seventh problem delivered and was followed by a correct eye-movement response (3). Dream report: “…in my dream I thought ‘I have to remember things’ and I heard the sounds and heard you talking while I was dreaming. I sat down in the car, and then I got a part of the assignment…. I was also really proud that I succeeded with a sum calculation, and that I heard them, and that I was aware that I was dreaming.” The participant stated that the source of the math problems “felt like a sort of radio in the car.”"