Onions are one of the many natural ingredients that can help you sleep better at night if had before bed. How? Onions are rich in L-tryptophan, a form of amino acid that acts as a natural sedative. It also helps in reducing stress levels which also aids a good sleep. It lowers down the level of sugar in your blood which results in a reduction of activity in the human body. Onions are also high Vitamin C which helps in lowering stress levels. However, it has not been proved that Vitamin C can aid better sleep.