Most observers describe Kagame's personality as one of seriousness and intelligence. Richard Grant, writing in London's "Daily Telegraph", described Kagame as radiating "a quality of intense seriousness that is both impressive and intimidating". Roméo Dallaire, commander of the United Nations Assistance Mission for Rwanda during the Rwandan genocide, described Kagame as having a "studious air that didn't quite disguise his hawk-like intensity". Kagame has a highly dominant personality, which he uses to enforce his rule and to ensure that his vision for the country is followed. American journalist Stephen Kinzer, who wrote the biography "A Thousand Hills" in collaboration with Kagame himself, describes him as "one of the most intriguing leaders in Africa". Kinzer credits Kagame with leadership skills that have fostered Rwanda's rebirth following the genocide, but also cites a personality of "chronic impatience, barely suppressed anger, and impulsive scorn for critics". In his interview with Grant, Kagame claimed he sleeps for only four hours per night, devoting the remainder of his day to work, exercise, family, and reading academic texts and foreign newspapers. When asked about his reputation for physically beating his subordinates by journalist Jeffrey Gettleman, Kagame said, "I can be very tough, I can make mistakes like that".