Washington: A good night's sleep fosters general health and well-being but now a new study highlights a more surprising outcome — greater feelings of gratitude. Social psychologists are finding that "prosocial" behaviour, expressing gratitude and giving to others, is key to our psychological well-being. Even how we choose to spend our money on purchases affects our health and happiness. "A plethora of research highlights the importance of getting a good night's sleep for physical and psychological well-being, yet in our society, people still seem to take pride in needing and getting, little sleep," says study co-author Amie Gordon of the University of California-Berkeley, US. "And in the past, research has shown that gratitude promotes good sleep, but our research looks at the link in the other direction and, to our knowledge, is the first to show that everyday experiences of poor sleep are negatively associated with gratitude toward others — an important emotion that helps form and maintain close social bonds," adds Gordon.