I've seen a patient confused as to why she couldn't lose weight and had trouble sleeping, feeling constantly exhausted, despite a perfectly clean diet of no junk food or sodas or any processed foods whatsoever. She kept track of her meals in a food diary for me to see proof of her good eating habits. In her journal I found the culprit immediately; she ate every night a large amount of fresh fruits for dessert because "fruit is healthy," so there couldn't possibly be something wrong with the food.
When it comes to eating the most damaging fruits at night, the one thing to take into consideration is their glycemic load and time at which our hormones are the least able to cope with such foods properly. Banana, with its high glycemic load, spikes your blood sugar and insulin at a time when you want to start burning fat and undergoing cellular repair, which interferes both with your metabolic functions and quality of sleep. Grapes and mangoes bring a big load of concentrated fructose, that is turned into triglycerides by your liver at night, when it slows down its metabolism dramatically. The watermelon, regardless of its seemingly innocent appearance, is basically made of pure sugar and has a very high glycemic index, flooding your system with glucose when the nighttime inactive metabolism doesn't know where to send it all. Bromelain and high levels of sugars in pineapples will stimulate your digestion and blood sugar levels, creating a hostile environment for the restful night. Oranges or other citrus fruits will create an acidic environment in the body due to being eaten horizontally while causing spikes in sugar levels that will ruin sleep architecture entirely.
While Western medicine started considering circadian rhythm only quite recently, TCM was already aware of the process thousands of years ago. It is known that each night our body repairs different organs in certain hours and that eating cold and sugary foods in that period will only make this impossible. While the knowledge of nutritional timing has always been around, now it has somehow been lost.