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23. It's really the psychological pattern of using food to cope. Depression or other psychological problems trigger eating. In many cultures, food is how you show love to children, so when we feel we lack love, we eat.

See also question 9.

It's true that infinitely psychologically healthy people will in fact be better at modifying their behavior, and not eating even if that's their first impulse, or even an exceptionally strong impulse. They will also be more able to force themselves to exercise, which helps set the human clock and get us to bed, and into darkness, earlier, as well. But too much exposure to light also makes us more depressed and saps our energy (metabolism), so getting more darkness would help us to exercise and improve our mood and increase our willpower as well as altering our appetite; by making us desire healthier foods, with or without willpower; with or without feeling well-loved.

Our appetites are very much regulated by the hormones that light regulates. Both the intensity of our desire for food (affected by the hormone ghrelin, amongst others, which hormone is controlled by darkness.) Although they can have many causes and apparent causes or focuses, it turns out that anxiety and depression are most easily tackled at the light switch.

See also question 26., “It's the stress of modern living.”