Most people face insomnia at some point. The worries of day-to-day life can keep us awake even if we are mentally and physically exhausted. A lack of sleep has medically been linked to premature aging and a wide array of medical problems, so it is serious business. One solution is the simple banana. Bananas contain the powerful chemical tryptophan, which will help knock you out. Dates, figs and surprisingly tuna also have tryptophan.