It’s official: A good night’s rest can, in fact, help mend a broken heart.

A recent study finds that when we go to bed feeling our worst… lonely, stressed, or sad… we often wake up the next morning feeling rejuvenated and ready to tackle life’s challenges.

According to the study, published in Proceedings of the National Academy of Sciences, negative feelings throughout the day… especially at bedtime… prompt our bodies to churn out the stress hormone cortisol. Elevated cortisol levels induce feelings of energy and optimism. As a result, we’re more likely to seek out positive social interactions that reduce stress.

Cortisol levels are highest thirty minutes after waking in the morning and gradually decrease throughout the day. By midnight, hormone levels have reached their lowest point.

The study shows that cortisol levels and daily experiences are intimately intertwined. Stressful experiences boost cortisol levels, and in turn, elevated cortisol levels often contribute to stress-reducing experiences.

Cortisol is often cast in a negative light… and for good reason. Long-term elevations of the stress hormone are associated with increased appetite and stress-associated weight gain. But scientists say short bursts of cortisol in the morning are actually beneficial, acting as a sort of rescue remedy for bodies in distress. In fact, chronically low cortisol levels can leave people feeling tired and sluggish, an observation that may help scientists understand chronic fatigue syndrome.

So the next time you go to bed feeling sad, take comfort in the knowledge that tomorrow is a new day!