Erections of the penis ( nocturnal penile tumescence or NPT) normally accompany REM sleep in rats and humans.  If a male has erectile dysfunction (ED) while awake, but has NPT episodes during REM, it would suggest that the ED is from a psychological rather than a physiological cause. In females, erection of the clitoris ( nocturnal clitoral tumescence or NCT) causes enlargement, with accompanying vaginal blood flow and transudation (. lubrication). During a normal night of sleep the penis and clitoris may be erect for a total time of from one hour to as long as three and a half hours during REM. 
There’s nothing like getting your workout out of the way while most of the world is still asleep—it makes you feel so accomplished! But fueling up beforehand can be a bit tricky. “I typically recommend that people wait an hour or two after eating to exercise. However, when you workout in the morning this can be unrealistic,” says Katie Cavuto , ., ., dietitian for the Philadelphia Phillies and the Philadelphia Flyers. “I recommend sticking with a small, easily digestible snack like 6-ounces of yogurt and a half cup of fruit.” This combo is easy on your stomach and gives you the rev your body needs. If dairy doesn't sit well with you or you’re a vegan, Cavuto recommends substituting in silken tofu for the yogurt and blending it with the fruit to make an energy-packed smoothie. (Make sure you're choosing the best creamy treat for your body by stocking up on brands that made our list of the Best Yogurts for Weight Loss .