If you are looking to increase your sperm volume overnight, there are a few things you can do. First, make sure you are staying hydrated by drinking plenty of water throughout the day. Next, eat foods that are high in antioxidants like berries and dark leafy greens. These nutrients will help to improve your overall reproductive health. Finally, avoid smoking and drinking alcohol as these habits can decrease sperm count. If you follow these tips, you should see an increase in your sperm volume within 24 hours.