YouTuber reveals what really happened to her body after using the sauna for an entire month

There are so many health crazes and fads these days that it's hard to know what's actually worth it to improve your body, yet one YouTuber decided to put the current fascination surrounding saunas to the test by going to one for an entire month.

You can always rely on YouTubers to find the answers to rather extreme challenges, and while few people would be willing to dive straight into a challenge as extreme as running five kilometers daily for someone new to the hobby, the results themselves are certainly fascinating to see.

Not every challenge needs to be this flashy or bold, however, and often the most intriguing video concepts are those that people watching can actually apply to their daily lives and see an improvement from.

That's certainly the case with a viral video from Keltie O'Connor, who put the health world's fascinating with saunas to the test by starting the habit herself, and it made an almost immediate difference to her life.

Keltie's primary goal with this challenge was to improve her heart rate variability (HRV), which measures the fluctuations in time between consecutive heartbeats with consecutive figures roughly within the 20-75 millisecond range being the most desirable.

One thing that she reveals she's struggled with is staying on top of her HRV alongside constant traveling and general anxiety, and she hoped that trips to the sauna would help mediate these variations when implemented into her busy life.

She follows a recommendation from popular neuroscientist Andrew Huberman, who suggests 60 minutes of heat exposure per week which can be broken up into intervals that suit your routine the best.

While she didn't take on the sauna every single day – as there are reportedly diminishing returns beyond that 60 minute mark – she opted for three 20 minute sessions each week for a month to complete the challenge.

To Keltie's surprise the difference was noticeable after the very first session, as her HRV improved by 15 – which she notes usually takes a month or two of not traveling to reach this point.

A big part of this is how easy she's finding it to get a good night's sleep, which is something she's struggled with in the past.

One of the most noticable post-sauna improvements was the quality and duration of her sleep (Getty Stock)

"After week one, I was just having really good sleeps. It's hard to say if its feeling good because of sleeping well or if I'm feeling good because of the sauna, but I can't fall asleep before 10.

"I love waking up before six but I can't fall asleep before 10, I just can't get sleepy, I can't stop my mind from racing, I have my sleepy tea, I have a nighttime routine, it doesn't matter.

"But, suddenly it was like I was laying on the couch at 9:30 p.m. and I was sitting here like, 'you know what, I could fall asleep at 10'," showing quite how transformative just a week's worth of sauna trips can be.

Detailing the improvements and changes she's witnessed following the challenge, she did note that there wasn't really any difference in her skin following the sauna sessions — but she didn't see any negative side effects, which are common when she's frequently traveling.

Her HRV – the key statistic – improved by an average of between 15 and 30 points, and her heart rate remained around the same. Her weight also remained within her usual natural fluctuations, and both her sleep and mental health saw a noticable improvement.

Additionally, she has kept up the sauna habit well beyond the initial month period, which is perhaps the best evidence possible that it's made a positive impact on her life in such a short period of time.