Depressants
Firstly, alcohol is a depressant. The chemical interaction with the brain basically slows down parts of it, which in humans, impairs things like reflexes, motor function, perceptive functions, etc. It also releases some psychological functions, such as the behavioral moderation that is common in sociological interactions. With less moderation, individuals tend to be more open in interactions, sometimes for better, sometimes for worse.
When considering these aspects of alcohol, there is definitely a character scenario for which alcohol would be helpful, and I think we can look to the very thing that Dwarves are known to be best at for guidance.
Perfectionism
Dwarves in every medium and story are master craftsmen. There are a couple of aspects that are key to crafting: repetition and a detailed eye. For basic material work and preparation, repeating systems that are meticulously tested are key. Alloying metals is a science that requires many tens or hundreds of hours to perfect, and then must be done the same way to maximize consistency in results. There are many other tasks that require the same level of perfect repetition to craft incredible works, especially larger ones, such as massive gates and structural metal work.
When it comes to making intricate items, a craftsman must have an uncompromising vision and eye for detail. Similarly for weapons, a single small defect can cause a weapon or armor to fail under stress when it matters most. Dwarven weapons and items are generally known to be near perfect examples of material work.
These factors lend themselves to an entire fantasy group that is given to perfectionism and potentially, as a cause of said perfectionism, general anxiety.
Anxiety
Perfectionism can be driven by a tendency to fear the worst from “underperforming.” Indeed, in my earlier comment on weapons and armor, I mention how minor defects in those things can cause failure at bad times. However, the entire species seems to tend to be surly and grumpy. In growing up with parents and family members that are perfectionists and grumpy, it would make sense that individuals would adapt to become anxious and perfectionist as well due to being exposed to negative consequences for failure during the learning phases of life. Experiences that cause that sort of perfectionism and general anxiety for failure could certainly make for excellent crafters; however, those experiences could also lead to crippling anxiety-driven behaviors, such as avoiding contact with others, choice fatigue and paralysis, and adrenal fatigue.
Side Effects of Anxiety
Of the many side effects of extreme anxiety, fear to make and maintain relationships is especially detrimental for a society. Without the drive and desire to be and work with other members of the society, it would eventually collapse. Cultural isolation leads to infrastructure degradation, supply problems, and other connected mental health issues. For reference, see the isolation caused by the response to the COVID pandemic. This sort of scenario goes a long way to explaining the dwarves general sense of isolation and grumpiness, and especially around other cultures, since Dwarves as a society might see any potential inability to be perfect as a stressor, and external cultural relations tend to be more tense than internal ones.
On a more individual level, choice fatigue and paralysis occur when every decision is burdened with anxiety and makes making future decisions harder and eventually impossible. Individuals experiencing decision paralysis will seize up when asked or forced to decide on something. The will either not respond or present apathy (“I don’t care, it doesn’t matter to me.”). This can lead to all sorts of personal and social issues, such as poor time management, avoidant behavior, and the inability to make functional, rational decisions.
Adrenal fatigue arises when an individual is constantly “on edge” to the point that their body’s endocrine system can’t produce enough hormones for normal function without sparking the “fight or flight” response. The physiological consequence of this tends to be an apparent lack of motivation to engage in basic life tasks such as cooking, cleaning, and productive work. If a whole society falls to this, then it would be catastrophic for the long-term outlook of the group.
A society facing an extreme version of this anxiety-based perfectionism would seek any method for reducing mental stress, and one particularly available substance immediately comes to mind.
Solution: Alcohol
Drinking alcohol on a moderate level in humans (1 to 2 standard drinks per day) has been know to decrease adrenal response, encourage social interaction in a positive way, and promote more sound sleep. In Dwarves, who tend to have a higher mass despite being shorter, this moderate drinking level would be higher, more akin to what we are familiar with in media. In short, if Dwarf culture drives all of them to have a crippling general anxiety disorder, then alcohol would be the self-medication that is cheap and readily available to all, and thus promoted within the culture and imbibed frequently.
Answer: Excessively Sober
Now, to actually answer your question an "excessively sober" Dwarf based on the above causes would likely display a few key characterizes:
- Generally avoidant of others, seeking isolation and safety at almost any cost.
- Nervous and anxious behavior that is dysfunctional in the immediate sense, it keeps them from holding conversation and focusing on tasks that are immediately important due to a general since of anxiety and fear
- Mood instability driven by noticing any perceived imperfection, i.e. if they notice that someone hasn't put something away properly or made some similarly small mistake, the Dwarf might immediately engage in anger displays
- And/Or people-pleasing behavior, seeking to ensure others are happy and satisfied with their work and presence, for fear of angering the other individual through imperfection or failure.