When a sign is in its shadow, I believe they are "coasting." There is no desire to access a higher consciousness, which includes incorporating the traits of the opposite signs to broaden their perspective. If you can't broaden your perspective and see beyond your constructs, potential for growth is severely limited.
The shadow, or low-functioning, side of each sun sign:
* PSA: This is only looking at the sign of the Sun. Your astrological birth chart has way more information about you as an integrated person and adds a more complete picture of your psychology. E-mail me for a reading at email@example.com if you would like more information regarding you as a whole person in the context of your natal chart.
Aries: When the Sun in Aries is vibrating low, their career and projects they instigate will overpower everything else. The will to achieve and to lead is very strong for Aries Suns and sometimes they can forget that people exist when they get really in the flow. Also, it's healthy to be focused on yourself and to make yourself your first priority, but an Aries can take this to an extreme place and emit an independence that is so strong that it is impossible for people to get close to.
Taurus: When the Sun in Taurus is operating from a place of shadow, their existence resides in the five senses. Theirs is a totally hedonistic perspective, only focusing on what makes them feel good at this moment. This can obviously leave room for addictions to food, beverages and sex because these comforts can literally leave a low-functioning Taurus in a state of bodily euphoria, which they can become attached to.
Gemini: When the Sun in Gemini is riding the struggle bus, their nerves are very visible. Be it through habits such as smoking or the way in which they are constantly fidgeting, they are nervous nellies with an abundance of restless energy that can be difficult to hide. Additionally, Gemini makes whatever it comes into contact with quite busy, so it can really scatter its energy and attention all around.
Cancer: When the Sun in Cancer is not doing well, everything is colored in a very subjective way. Cancer is ruled by the moon, so their perceptions tend to wax and wane in a similar way. A well-developed Cancer Sun can dig themselves out of their shell only to realize that some things are much better and easier viewed through a pragmatic lens, so when a Cancer can't access that point, the ego and self-expression change hour-to-hour.
Leo: When the Sun in Leo is presenting with shadow, they can either resemble Narcissus with a serious superiority complex OR they can really allow for their self-worth to become contingent on the feedback of others. Negative feedback or criticism that is less constructive is a part of every day life because not everyone is going to like you the way you feel that you deserve to be liked! A Leo Sun on the low-side can have a very hard time seeing that and can really alter themselves in different situations to please and receive adoration and good feedback from others. In either case, they're not really allowing others around them a chance to shine, and people generally don't like that.
Virgo: A shadow-side Sun in Virgo looks stressed out and seriously overworked and because of that they have SO much resentment that creeps in. In their eyes (and this may very well be true), no one does as much as them and no one can do it as well and with the amount of precision that they can. As a result, their plate is usually full of work, sometimes unnecessarily, and they can't escape it and have a hard time not thinking about it when they're supposed to be taking breaks, or taking breaks at all. Sometimes, because the body connection with Virgo is so strong, this can result in some serious digestion and stomach problems. Watch for the tendency to be too critical of your environment and invite in some relaxation and ease.
Libra: A low-functioning Sun in Libra can't make a decision without consulting their significant other, or if they're single, with all of the people in their life. It's like they can't trust their gut feelings about situations that require boldness of action, so they may allow for these to pass them by. A lot of Libras may turn to social fun or substances to drown out this inability to listen to themselves, which only breeds more indecision. Sticking to a decision that they made themselves without consulting anyone else is a great way to feel self-assured, and sometimes you have to fake it until you make it.
Scorpio: A shadow Scorpio Sun is existing in a world full of chaos. Their ego-connection to power may be a little bit too strong and the will to dominate others subconsciously could be even stronger. They regularly engage in manipulation tactics to get what they want out of people, and emotional manipulation is number one. Scorpio Suns have psychic knowledge of the darker underpinnings of the outside world because they themselves have experienced SO much darkness, so the tendency is to use that gift for evil and not for good, which comes around over and over again.
Sagittarius: A Sagittarius Sun that has wandered in from Strugglesville is in a perpetual state of either drunkenness or wanderlust. Making plans with this human can be very difficult as it feels like even a lunch date holds them back from accomplishing their VERY broadly defined ideals. A tendency to not only neglect but straight-up avoid the details is present in this person, as well as a tendency to also avoid serious emotional displays or darkness in any form. Details and darkness are a part of life and it's important that this individual understands that and develops even a small place for those things.
Capricorn: A Capricorn Sun that is on the low-functioning side is a workaholic. They avoid the realms of emotions, human relationships and subjectivity and just cast themselves out into their works with a tunnel-vision focus on their great works and their legacy. Shadow-side Capricorn can also see things in a shade of gray and be very prone to depression because of the realistic lens through which they see the world as well as themselves in the world. This can prevent them from having unpredictable and spontaneous experiences that could wind up teaching them something important about themselves or other people.
Aquarius: An Aquarius Sun that is showing up in shadow is very much not concerned about themselves at all. Someone who gets lost in a cause and helping the collective consciousness to the point where even taking showers or eating nourishing meals is forgotten about comes to mind when I see the Sun in Aquarius isn't in a good place. Another tendency present looks like viewing everything from this place that is so high-minded that it is in a tower lightyears from this planet without any subjectivity or emotion or drive to get what THEY as an individual person want.
Pisces: A Pisces Sun that is swallowed by their low-side very frequently gets lost and confused. Escapist tendencies, drug abuse and codependency shows up here only because they are already absolved of their ego and this material world. This Pisces regularly gets lost in the shuffle and has a really hard time directing itself to work or the future or anything even remotely mundane.