Popcorn Tryptophan, the same amino acid found in turkey, is also in popcorn. Because it helps create the sleep-inducing neurotransmitter serotonin in our brains, it can be helpful in falling asleep. But skip the butter and oil; air-popped is best.Air-popped and eaten plain, popcorn is a healthy whole grain food that is low in calories (about 30 calories per cup) and high in fibre (about 1g per cup), especially when compared to snacks like crisps. ... But oil-popped and flavoured popcorn is a different story.