As Buffy the Vampire Slayer, Sarah Michelle Gellar was a teenage girl endowed with supernatural powers and destined to battle demons, vampires, and other evil creatures from the underworld.

Despite her incredible physical strength, however, Buffy struggled with her emotional wellbeing – something which her friends often failed to realise, as they always viewed her as the tough one of the group.

It was a staunch reminder that anyone can be affected by mental health issues, and now, in a powerfully candid Instagram post, Gellar has detailed her own battle with postnatal depression.

Read more: Fearne Cotton opens up about being diagnosed with depression

Sharing a photo of herself with her and Freddie Prinze Jr’s daughter, Charlotte, just a few months after her birth in 2009, Gellar explained that there was more to the picture than first meets the eye.

“Having kids is wonderful and life-changing, and rarely what you’re prepared for,” revealed the 40-year-old.

“I love my children more than anything in the world. But, like a lot of women, I too suffered with [postnatal] depression after my first baby was born.”

Gellar continued: “I got help and made it through, and every day since has been the best gift I could ever have asked for. To those of you going through this, know that you're not alone and that it really does get better.”

She ended her message with a call to action, referencing President Donald Trump’s new plans to replace America’s Affordable Health Care Act (otherwise known as Obamacare).

“And if you believe that postpartum depression should be covered by healthcare, please take a moment and go to callmecongress.com today, find your rep's numbers and let them know,” she said.

Read more: Hayden Panettiere takes time out as depression “affects every aspect of my life”

Gellar hopes that her personal struggles will encourage others to seek help for their own mental health issues – and other big names have been similarly open of late.

A few months ago, Chrissy Teigen penned an essay about how her life changed for the better after doctors diagnosed her with postnatal depression and anxiety.

“I remember being so exhausted but happy to know that we could finally get on the path of getting better,” she wrote. “I started taking an antidepressant, which helped. And I started sharing the news with friends and family—I felt like everyone deserved an explanation, and I didn’t know how else to say it other than the only way I know: just saying it.

“It got easier and easier to say it aloud every time.”

And, during an interview with Good Morning America earlier this year, Hayden Panettiere gave fans an update on her nearly two-year mental health battle, revealing that she feels she can take some positives from her experiences.

“It takes you a while, and you feel off,” she told show host Lara Spencer. “You don’t feel like yourself, [but] women are so resilient, and that’s the incredible thing about them.

“I think I’m all the stronger for it. I think I’m a better mum because of it, because you never take that connection for granted.”

Speaking about the feeling she experienced after the birth of her daughter, Kaya, in 2014, Panettiere added: “I think it helped me identify what was going on and to let women know that it’s OK to have a moment of weakness,” she said. “It doesn’t make you a bad person, doesn’t make you a bad mother. It makes you a very strong, resilient woman.

“You’ve just got to let it make you stronger.”

The symptoms of postnatal depression

Mental health is an issue that affects many of us, but women in particular can be vulnerable to issues: the most recent figures from the NHS show that one in five women in the UK have reported a mental illness in recent years, compared to one in eight men.

While the symptoms of postnatal depression can be complex and vary widely between different people, doctors have said that the most common is that “you feel increasingly depressed and despondent. Looking after yourself or your baby may become too much.”.

Other symptoms include:

• Loss of interest in the baby
• Feelings of hopelessness
• Not being able to stop crying
• Feelings of not being able to cope 
• Feelings of guilt and self-blame
• Not being able to enjoy anything
• Memory loss
• Feeling unable to concentrate
• Low self-esteem
• Excessive anxiety about the baby
• Panic attacks
• Sleeplessness
• Extreme tiredness
• Aches and pains
• Feeling generally unwell
• Anxiety
• Loss of appetite 

There are many other symptoms of postnatal depression and you’re unlikely to experience all of them at once.

If you or someone you know would like advice on postnatal depression, visit the NHS website here or Mind's website here.

Images: Rex Features