Capital’s Sian Welby said TikTok solved ‘uncontrollable tiredness’

The radio presenter warned others to the danger that most of us 'don't know' about when driving - especially in summer

12:32, 22 Jul 2025

The radio host 'thought she had an issue' after getting tired while driving for long distances(Image: Mike Marsland/WireImagevia Getty Images)

Sian Welby thought something was wrong with her after she found herself battling against 'uncontrollable tiredness' while behind the wheel[1]. However, she never imagined her vehicle could be to blame.

Speaking to listeners of the Capital Breakfast radio programme she presents alongside Jordan North and Chris Stark, Sian offered her findings to "anyone who drives"[2]. The 38-year-old broadcaster claimed it was only through a random browse on TikTok[3] that she was able to pinpoint her issue - and it is a feature found in most modern cars[4].

In a post shared with her 274,000 Instagram followers, Sian said: "We had lorry drivers and taxi drivers[5] texting in saying the button had been on in their cab the whole time and they never noticed it!

So dangerous and most of us don't know about it!"

She told her co-hosts that she "thought she had a bit of an issue" during car trips that went over half an hour, particularly those involving a stretch of motorway. She explained: "I didn't know if it was sort of the rhythmic motion of the car on motorways or the mundane view you've got of constant tarmac, but it would send me to sleep - and I'm talking uncontrollable tiredness.

"I started thinking 'what is wrong with me?'. Even if I had a good night's sleep, I'd be pinning my eyes open on these long journeys."

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Sian said that a casual browse through TikTok led her to a clip which claimed that viewing it "could save your life".

She thought it was most likely going to be "a load of nonsense" but was hooked nonetheless - and it turned out it was actually the answer to her driving problem.

The broadcaster, who also occasionally appears on ITV's This Morning, explained how driving with windows down on motorways often results in a "horrendous" noise in your ears, reports the Mirror[6]. What most people would do for a cool and refreshing breeze is using the air conditioning system (provided your car has one).

She went on: "When you've got air conditioning in your car, you've got two buttons, and there's one that shows a car with arrows-the recirculation button. A lot of us were told that it would save energy if you put that on because it recycles the air inside your car and it cools down quicker - that's true.

"However, apparently, it's not designed to be left on and it can cause drowsiness.

So I thought, right, this could be a load of nonsense but if I get into my car and that button is on, it might be why I'm getting tired."

The recirculation button looks like a car with an arrow going around inside it(Image: Yusuke Ide via Getty Images)

Sian went out to check and, sure enough, that button was on in her car. She added: "I turned it off and did a three-hour motorway journey the other day - didn't feel tired once."

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This isn't simply psychological - there's genuine scientific evidence behind it.

Research suggests that recycled air within vehicles contains reduced oxygen concentrations and elevated carbon dioxide levels.

Certain vehicles may come equipped with a built-in timer that automatically deactivates the recirculation after a set amount of time, allowing fresh air into the vehicle's cabin, but some won't turn off unless you do it yourself.

The air conditioning recirculation button is best used for short periods, typically not exceeding 20 minutes.

References

1. ^ behind the wheel (www.walesonline.co.uk)
2. ^ "anyone who drives" (www.walesonline.co.uk)
3. ^ a random browse on TikTok (www.walesonline.co.uk)
4. ^ modern cars (www.walesonline.co.uk)
5. ^ taxi drivers (www.walesonline.co.uk)
6. ^ the Mirror (www.mirror.co.uk)