Jessa Gamble (born April 25, 1979), née Sinclair, is a Canadian and English author and co-owner of the science blog The Last Word on Nothing. Her book, The Siesta and the Midnight Sun: How Our Bodies Experience Time (Penguin Group), documents the rituals surrounding daily rhythms. Along with local languages and beliefs, these schedules are losing their global diversity and succumbing to what Gamble calls "circadian imperialism." The foreword was written by Canadian broadcaster Jay Ingram.