Nitric oxide supplements are taken to either increase both vascularity and circulation, or to induce greater growth hormone release. Both circumstances require daily maintenance, only at different times and in different ways. For an individual seeking greater vascularity, take nitric oxide supplements an hour before the gym. For an individual seeking increased growth hormone levels, take nitric oxide supplements before bed without any carbohydrates that night. Nitric oxide products usually contain different forms of arginine; however, newer products implement glycerol and blood thinning herbs.