Since nibs are directly from the cocoa tree, they contain high amounts of theobromine.
en.wikipedia.org Most alkaloids are weak bases, but some, such as theobromine and theophylline, are amphoteric.
en.wikipedia.org As with caffeine, theobromine can cause sleeplessness, tremors, restlessness, anxiety, as well as contribute to increased production of urine.
en.wikipedia.org Guarana, a prime ingredient of energy drinks, contains large amounts of caffeine with small amounts of theobromine and theophylline in a naturally occurring slow-release excipient.
en.wikipedia.org Hot chocolate is traditionally a bedtime drink but this contains high levels of xanthines (caffeine and theobromine), which are stimulants and so may be counter-productive.
en.wikipedia.org