Most people think that phones are a bad thing for anxiety. Parents, in particular, believe phones are terrible for the mental health of children, teenagers and young adults. So, what is the truth? While I was writing my book You Don’t Understand Me, which addresses the mental health of teenage girls and young women, I felt I had to get to the bottom of the relationship between phones and anxiety. And to be honest, it doesn’t look great. Since smartphones came out in around 2000, there has been a steady decline in the mental health of young people. But as we know, correlation does not necessarily equal causation.

What I have observed clinically is that rather than being the cause of the problem per se, phones seem to act as a catalyst to our emotions. This can be a positive thing, when it allows us to connect with friends and family; share happy news; photos or jokes. It also allows marginalised communities to find each other.

However, humans are wired to foresee danger and our minds can quickly spiral from an initial trigger to create catastrophic, wholly imaginary circumstances, which our bodies respond to as though they are true. In your head this goes something like: “Some of my friends are meeting without me > they don’t want me there > they don’t really like me > nobody really likes me > I am fundamentally unlovable and will die alone.”

The phone contributes to this in a number of different ways. First it allows us to know our friends are meeting without us. There was something in “ignorance is bliss” and now there is no ignorance. We know, and we get to sit on our sofa in some old jogging bottoms on a Saturday night and compare our inside worries, our worst sides, our ugliest self, with endless, perfectly curated versions of other people’s lives. And guess what? That makes us anxious and unhappy.

Our phone is like a scab we know we shouldn’t pick. We know it is making us feel bad seeing our rich friend on a weekend trip away with her gorgeous partner; we know we should put our phone down and go and do something constructive and positive – some yoga, a walk, a hot bath with candles. Look, there is someone on Instagram with a perfect bathroom and a beautiful body showing us what we should be doing, and we are just sitting around scrolling – no wonder no one wants to hang out with you. In this way, your phone can trigger a second round of self-judgment about how lazy or worthless you are.

The phone intensifies a comparison culture that can leave you feeling not good enough in every single aspect of life: not thin enough; not successful enough; not tidy or organised enough; not living in a nice enough home; not well-read or smart enough.

And while research into the effects of this on mental health is in its infancy, there is particularly damning research in relation to viewing photos of perfect bodies, which is shown to increase body dissatisfaction, with a link to eating disorders. Even when we know the images are doctored, and even when they are shown in relation to fitness, they still impact on body dissatisfaction.

So some of the questions I ask my patients about their phone use are:

Are you using your phone to connect to people or to compare to people? The former is positive for mental health but the latter will likely increase anxiety.

Is there a tipping point where phone use changes from positive to negative? Do you notice this tipping point? And can you put your phone away then? My experience suggests it is just at this point that the phone is at its most magnetic.

Is your phone getting in the way of you doing things which are positive for mental health? Phone use is perhaps at its most damaging when it gets in the way of sleeping, eating regularly, being outside and moving your body, all of which are important for wellbeing.

Research suggests that there may be a sweet spot with mobile phone use, after which the screen stops being helpful or fun and starts having a negative impact on wellbeing. An analogy to drinking is helpful: a couple of glasses of red wine can be relaxing; a bottle a night is not so helpful. And like with drinking, some people find it difficult to stop just at the point when they should.

So if you are experiencing anxiety, think about your phone use – think about how much time you spend on it and on what kind of content. Readdressing this might be one important key in unlocking a less anxious life.

Phone and internet use is best when it is in line with our other values rather than taking us away from them. There is often a wafer-thin line between these two, but I would look for phone use which is driven by:

Connecting to people. A shared family WhatsApp group or FaceTiming old friends can be great. But this is not the same as seeking out ex-schoolmates to see how successful they are – that is comparison.

Compassion for yourself. An online yoga class, meditation app or an audiobook at bedtime are examples of nourishing ways to use the internet. Watching back-to-back episodes of a box set into the night is not compassionate; it is getting in the way of the self-care of sleeping.

Creativity. The phone has allowed a democratisation of creativity, particularly in photography, but also in sharing humour, craft, art and writing. Teenagers in particular have demonstrated incredible creativity on platforms such as TikTok but we need to have caution for content that is reductive rather than expansive, especially in relation to beauty or sexuality.

Curiousity about difference. Phones can turn a mild disagreement into a massive row, with positions becoming entrenched. Can you use your phone to explore new ideas, rather than get stuck in a rut?

• You Don’t Understand Me: The Young Woman’s Guide to Life, by Tara Porter published by Lagom (14.99), order your copy at guardianbookshop.com.