New research in Thursday's New England Journal of Medicine suggests that some blind people have a way of sensing light, even though they cannot see it. The discovery may yield clues on how the brain keeps time. Many blind people suffer from insomnia; unable to sense light, their bodies fall behind real time by about a half hour each day. Yet a third of the 1 million Americans who are completely blind do not experience the problem. Dr. Charles Czeisler, a member of the team that conducted the research at Brigham and Women's Hospital in Boston, speculates that removing the eyes of blind people, a common practice, may sometimes be a mistake, since it appears that even sightless eyes often can register light.