After a night of tossing and turning in the bed, you finally nod off to sleep. Moments later -- or so it feels like -- the alarm chimes, and it's time to get up. Needless to say, this isn't the best way to start the day. A study published in the journal Science tracked 909 working women's mood shifts throughout the day. Aside from work-related stress, not getting enough quality sleep was the top predictor of unhappiness among the subjects [source: Carey].
Also, a psychology professor at the University of Michigan calculated the happiness boost people get from sleeping an extra hour each night as equivalent to receiving a $60,000 annual raise [source: Barnett]. This impressive effect likely relates to brain chemistry. The brains of sleep-deprived people are more sensitive to the effects of cortisol, a stress hormone [source: Franklin Institute].
The link between sleep and happiness begs the question of correlation versus causation. Does poor sleep make us unhappy, or is unhappiness hindering sleep? It probably depends on individual situations. Someone working 60 hours per week may be suffering from overwork and sheer lack of sleep time. On the other hand, symptoms of unhappiness, such as stress and television, don't promote quality rest, either.
Tackling the sleep issue may require a multipronged approach. Evaluating stress levels and exercise routines are smart places to start. After all, when you don't prepare your body for bedtime, nodding off can prove challenging no matter how happy you feel.