Studies have shown that meditation increases melatonin levels in your blood. Melatonin is an important neurotransmitter that regulates the sleep-wake cycle. Our melatonin levels naturally rise after sunsets. And it begins to fall when the sun rises. These studies have found that meditation decreases sleep-interfering cognitive processes of negative feelings, like angst, fear, and worry. If you have trouble falling asleep, then try going through a guided meditation before you sleep. And learn more about the sleep experiment.
Source: Deepak Chopra on Youtube