The Harry Potter author, 50, responded after Twitter user Marina, 18, reached out to her on the social media platform.
'@jk_rowling could you please teach me how to scare the dementors that have been living under my bed? i'm tired of being sad all the time', Marina wrote.
Dementors are creatures from the Harry Potter world that 'suck' the happiness out of a place or person. 'Dementors are among the foulest creatures that walk this earth. They infest the darkest, filthiest places, they glory in decay and despair, they drain peace, hope, and happiness out of the air around them... Get too near a Dementor and every good feeling, every happy memory will be sucked out of you,' the novels explain to the readers.
J.K., real name Joanne, quickly replied 'They're bothering a unique, valuable human being who deserves happiness. Ask for help. Don't fight alone. Big hug.'
@jk_rowling could you please teach me how to scare the dementors that have been living under my bed? i'm tired of being sad all the time— bellatrix black (@mtrssmustdie) February 8, 2016
They're bothering a unique, valuable human being who deserves happiness. Ask for help. Don't fight alone. Big hug. https://t.co/V8ocAHN1Ll— J.K. Rowling (@jk_rowling) February 8, 2016
After J.K., who has over 6.7 million Twitter followers, publicised Marina's plea with a retweet, more advice from fans all over the world began to pour in.
'And don't forget to eat chocolate every now & then! *hugs from another person fighting her dementors*', one wellwisher wrote, while another added 'Expecto patronum comes in many forms <3 You are not alone, and we're here for you. <3'
Some fans sent gifs of adorable animals to put a smile on Marina's face.
Others gave practical advice, like using a lamp to ward off darkness, or finding activities to make her happy.
Marina was clearly overwhelmed by the heartwarming response, later tweeting 'you are all so sweet oh my god ❤️ potterhead love is the best kind of love', and 'oh god im going to sleep now with a big smile on my face.'
This isn't the first time J.K. has supported her fans through social media - she's well known for bestowing wisdom and inspiration, like this exchange in May 2015.
@jk_rowling This may get lost in the noise..but what would you say to someone who has failed to find meaning and wants to finally give up?— Brocaesar (@BrocaesarTV) May 4, 2015
.@BrocaesarTV And I'd say, the world is full of wonderful things you haven't seen yet. Don't ever give up on the chance of seeing them.— J.K. Rowling (@jk_rowling) May 4, 2015
1 in 4 people in the UK alone are dealing with a mental health problem, and figuring out how to cope with depression is never easy.
However, there is help available - for more information, visit mind.org.uk or speak to your GP to discuss your options.