Insomnia
Really Common
Common Causes: Ongoing pain or mental strain from external factors. You feel sleepy consistently though your eyes refuse to close.
Effects: While taking a long rest, there’s a rising chance that your sleep will be disrupted and you will not be able to complete your long rest. When taking a long rest, roll a d100. If you get above a 10, you will complete your long rest. The DC increases by 10 every time you take a long rest until you fail, the DC will then reset to 10.
Warning: Your insomnia can worsen to such a state that you can’t even benefit from brief and short rests.
Anxiety
Really Common
Common Causes: Ranges from the overuse of substances to consistent and intense stress over a long period of time.
Effects: 3 times per day, the DM can call upon an anxiety attack upon your character. Your character must make a wisdom will save with the DC set by the DM depending on the situation. Upon a failure, you begin to panic like your life depends on it. You either gain the incapacitated condition for a few minutes or gain the frightened condition with your source of fear being the unknown.
Warning: If the source of the anxiety attack is actually important or significant to your character specifically, you can either go nonverbal or become paralyzed upon failing the wisdom will save.
Extra Warning: An anxiety attack can quickly escalate into a full scale panic attack, meaning your character takes on the effects of the Unconscious Condition while still remaining conscious.
Bard’s Revenge
Really Common
Common Causes: You hear a song that you really really hate, but your mind holds onto the recollection of the tune.
Effects: In the back of your mind, every now and then, a song you’re annoyed by plays and distracts you. You gain a -1 bonus to perception and investigation checks. .
Depression
Common
Common Causes: Can come from many, many places. Environmental factors, trauma, genetics, etc.
Effect: At the beginning of the day, flip a coin. If you call it incorrectly, you have a -1 bonus to all of your skill checks until your next long rest. And when you take a long rest, flip a coin. If you call it incorrectly, the DM chooses a skill check for you to have a -1 bonus to until your next long rest.
Hydrophobia
Common
Common Causes: A traumatic event in your past involving water that makes your mind and body reflexively avoid anything relating to it.
Effect: When near or in a body of water, you are put under a frightened condition. If you are in water under the frightened condition, your walking and swimming speed becomes 0 as you are too afraid to move.
Dementia
Common
Common Causes: Injury to the brain or development of Alzheimer's (alongside variants)
Effects: You instantly gain a -2 to memory checks. You gain disadvantage in all intelligence skill checks as well. As time passes, the negative bonus to memory starts to increase to a max of -10.
Warning: Dementia can very quickly evolve into some of the variants of amnesia, either not allowing the accessing of old memories or the creation of new ones.
The Twisted Tongue
Common
Common Causes: Unknown
Effects: Gain a -2 to persuasion as you cannot speak without cursing, meaning you will never sound distinguished enough to properly persuade someone.
IED
Uncommon
Common Causes: Can come from many, many places. Environmental factors, trauma, genetics, etc.
Effect: Once per day, you must make a wisdom will save set by the DM. Upon a failure, roll a D20. Almost as if a switch flips in your brain, and you must spend an amount of minutes equal to what you rolled on the D20 impulsively expressing your anger. This can mean physical harm to the environment, others, or even yourself.
Tourette’s
Uncommon
Common Causes: Not clear, but theories point to genetic abnormalities.
Effect: Select a collection of words that are important to you. If you hear those words at any point, you immediately lurch out and repeat it Out loud. This effect will turn your stealth from whatever it was to the result of a natural 1.
Gambling Addiction
Uncommon
Common Causes: A mixture of genetic factors, stress and mental issues, as well as being exposed to gambling from a young age.
Effect: At the mention of risk taking or outright gambling, you must roll a wisdom will save of 5. Upon succeeding, the DC increases by 1 for the next time you need to roll and you resist the temptation. However, upon a failure, YOU MUST GAMBLE AND TAKE THE RISK BABY!
Narcolepsy
Uncommon
Common Causes: Lack of chemicals in the brain that regulates how wakeful you are.
Effect: Once per day, you must roll a tolerance save set by the DM. Upon a failure, you are knocked unconscious for about 5 minutes.
The Golden Vision
Rare
Common Causes: Coming into too much wealth without enough healthy advising.
Effect: You become obsessed with gold and the value of money. Whenever around anything valuable, you must roll wisdom will saves of increasing difficulty, set by the DM, to hold yourself back from instantly trying to take whatever you see. Upon failing the will save, you will stop at nothing and use everything in your arsenal to get what you see as valuable.
Post Traumatic Stress Disorder
Uncommon
Common Causes: Experiencing a prolonged critical stressful event, the brain recoils at even the slight recollection of the event.
Effects: You must go calculate your sanity pool immediately, rules on the main disease page. Minimum DC 15 but can be higher, the DM can choose to have the character roll a wisdom will save at the mere mention of whatever caused your PTSD. Upon a failure, your mind temporarily shuts down, making you incapacitated until you succeed on the will save, you can try once per 3 minutes. You also experience a symptom of a related illness until you succeed on the will save.
Depressive Episode
Bursts Of Angry
Paralyzing Levels Of Panic
Effects Of Other Illnesses You Can Think Of
Warning: After having PTSD for long, you may gain another mental illness just from PTSD itself. Whenever you have a PTSD attack, it activates the effects of all other mental illnesses as well.