Alcohol loosens your inhibitions and pushes you deeper into the abyss. While you wouldnt have killed yourself sober, the answer might look different after a few bottles. Its the same reason firearms have an influence on the suicide rate. Pulling a trigger is just a lot less of a hurdle then most other methods.
This makes me wonder what the actual rate of suicides are performed under influence compared to completely sober. I have a feeling the latter is extremely rare.
