Young college women (no. = 120) received, on three different occasions, 12 oz water, aspartame-sweetened beverage, and sugar-sweetened beverage, separated by weekly intervals. Changes in mood were assessed by administering test questionnaires before and 1 hour after the beverages were drunk. Mood tests employed were the Stanford Sleepiness Scale (SSS), the Visual Analogue Mood Scale (VAMS), and the Profile of Mood States (POMS). Changes in mood were similar following consumption of water or the aspartame-sweetened beverage. However, the ingestion of the sugar-sweetened beverage was followed by increased sleepiness during the last half of the one-hour observation period (p less than .002).