The women who’d had six hours of sleep or less were in a different league of unhappiness, almost, than those who’d had seven hours or more. The gap in their well-being was so extreme that it exceeded the gap between those who earned under $30,000 annually and those who earned over $90,000. (In newspapers and magazines, this finding is sometimes re-reported as “an hour extra of sleep is worth a $60,000 raise,” which isn’t exactly right, but close enough.)
