Adam Haar Horowitz is the first to admit that whispering to strangers as they fall asleep “seems a little creepy.” He’d been mulling over the idea with fellow MIT master’s student Ishaan Grover a few years ago while thinking about ways to influence the dreamlike visions people see at sleep onset, a state known as hypnagogia. The pair wondered if quietly saying words or phrases to people in hypnagogia might influence the content of their thoughts and visions, thereby serving both as a tool to investigate human cognition and, ultimately, as a means to help people wield control over their dreaming brains.
Haar Horowitz didn’t end up whispering into strangers’ ears, but he, Grover, and other collaborators did find a way to execute the basic concept, using a more practical solution: a device that fits into a person’s hand to monitor changes in heart rate, muscle ...