The introduction of new body-worn technologies is transforming the way people interact with their environment and one another, and even with themselves. Social and environmental psychology studies of human-technology interaction pose as many questions as answers. Monitors can tell adults how often they wake up during the night, the duration of sleep, time spent in bed, and times of awakening. Sleeping patterns convey personal details about individuals, such as insomnia or compulsive obsessive disorder, sexual activity, workaholism, likely performance in stressful jobs, and other things. Wearables can also look outward, reconstructing the world with location coordinates, current speed traveled and direction, rich high-resolution photographs, and audio capture. Bystanders are likely to be as oblivious to data collection from wearable devices as they are from data collection of private investigators using covert devices.