Lucy Hale has described hitting "rock bottom" as the "greatest gift" of her life.

The 36-year-old actress has celebrated four years sober and marked the milestone by reflecting on how far she has come since she found herself in a "dark chapter" before turning her life around.

She wrote on Instagram: "4 years ago, I reached a very dark chapter and my personal rock bottom. It's wild to say, but that ended up being the greatest gift and biggest turning point in my life.

"The path hasn't always been smooth. There's been pain, discomfort, loneliness, and deep self-confrontation. But sobriety handed me back my life. I am deeply grateful for every single moment that has brought me to this point.(sic)"

The Pretty Little Liars star urged others struggling with addiction to "keep going" and to do their best to seek help.

She added: "If you're struggling, please know this: there is always a chance to begin again. Keep going. Keep speaking your truth. Ask for help. And remember that are so worthy of a life you're proud of. Your existence matters, and so does the story you carry. It DOES get better [heart emoji].

"I've realized that darkness isn't always something to fear. It's often the very thing that leads us toward the light.(sic)"

Her former Pretty Little Liars co-star Tyler Blackburn was among those to offer support in the comments.

The 39-year-old star shared a heart emoji and wrote: "So proud of you!"

And Ashley Newbrough, who worked with Lucy on Privileged, wrote: "You radiant thing [heart emoji] beyond proud of you."

Last year, Lucy reflected on the "pure miracles" she had experienced since getting sober.

In a post on Instagram, she explained: "Damn. 3 years ago today, I began my journey in remembering who I am. Since then, I've experienced moments that can only be described as pure miracles and magic.

"I am deeply grateful every day - for the people who have been guiding lights, for a power greater than myself that loves me unconditionally, and for my own perseverance in not giving up.(sic)"

Lucy previously admitted she first turned to alcohol as a teenager because she felt "alone and misunderstood" and wanted to quit many times but suffered numerous relapses before finally getting sober.

She told People magazine: "Since a very young age, I always felt alone and misunderstood. So as a teenager, I found alcohol - which of course shut my brain off. And it worked for me for a while, until it turned really dark ...

"I always had a desire to change, but with any form of addiction, you become powerless to this obsession. I definitely had to go through my own process of getting sober.

"It took many, many, many years, many relapses, many dark moments, many falling on my face quite literally, but figuratively as well to figure out what was working in my life, finding out why I was drinking, because removing alcohol is just one part of it."

Lucy believes having a creative career in acting probably saved her life.

She added: "If I'm perfectly honest, without my career and without that creative outlet, I don't know if I would've made it."