If your phone use feels out of hand and your mood has been low or anxious, it is natural to wonder which one is driving the other. Some people ask whether the phone is making them depressed. Others ask the reverse: whether they scroll because they already feel bad.
The honest answer is that both can be true, and the research is clearer on some parts than others. This article separates what has been tested from what has only been observed.
Can phone addiction cause anxiety?
It is linked to anxiety, though the evidence on that point is correlational.
A 2025 meta-analysis in Psychological Bulletin pooled 71 studies covering about 98,299 people. Heavier short-form video use was linked to poorer attention and, most strongly, poorer inhibitory control. It was also linked to more stress and anxiety.
The word to hold onto is "linked". These were correlational studies, so they show that the two travel together, not which one leads.
Source: Nguyen et al., Psychological Bulletin, 2025.
Can phone addiction cause depression?
The evidence here is suggestive, not settled.
A 2026 survey of 439 people in Psychological Reports looked at "brain rot" (cognitive fatigue). It was linked to depression indirectly: first through burnout, then through stress and anxiety.
That is one survey, and surveys cannot show cause. It does fit what many people describe, which is feeling drained first and low afterwards.
Source: Batmaz, Özsağır & Arslan Şekkeli, Psychological Reports, 2026.
Is there any evidence that cutting back helps?
Yes, and this is the strongest piece of evidence available.
Castelo and colleagues published a randomised trial in PNAS Nexus in 2025. It involved 467 participants whose mobile internet was blocked on their smartphones for two weeks. Calls and texts still worked. The trial reported improvements in mental health, subjective well-being and sustained attention. Increased nightly sleep was one mechanism.
Random assignment is what makes this different from the studies above. It is the closest we have to evidence that reducing phone internet use can improve how people feel.
It does not say that phones are the only cause of anxiety or low mood, and it does not tell us what happens over years.
Source: Castelo et al., PNAS Nexus, 2025.
What might be happening in the brain?
Some small studies hint at mechanisms, though none of them settle the question.
An EEG study of 48 people found that a higher short-video addiction tendency went with lower prefrontal theta activity during an attention task, and with lower self-control. A separate fMRI study of 56 people found that cognitive-control regions were less active while people watched short videos, most of all for videos they preferred.
A study of 68 college students found that a mobile-phone-dependent group had lower grey matter volume in frontal control regions than controls. That one is correlational and small, so it cannot tell us whether phone use changed the brain or whether people with those differences use phones more.
Taken together, these studies are consistent with a story in which heavy use sits alongside weaker self-regulation. They are not proof of damage, and nobody should read them as a diagnosis.
Source: Yan et al., Frontiers in Human Neuroscience, 2024; Wang et al., Frontiers in Psychology, 2016.
Does sleep sit in the middle of this?
It may, though the evidence is limited.
A 2025 meta-analysis in Frontiers in Psychiatry pooled 21 cohort studies covering 548,338 people. Each extra hour of daily screen time was associated with a bedtime about 13.2 minutes later, roughly 3 to 5 minutes less sleep, and higher odds of difficulty falling asleep.
That study links screen time to sleep only; it does not show that sleep explains mood. Castelo did find increased nightly sleep as one of the mechanisms in the trial, which is consistent with sleep playing a part.
Source: He et al., Frontiers in Psychiatry, 2025.
Which way does it run: the phone or the mood?
Possibly both, and the research as it stands cannot fully separate them.
In everyday experience, feeling anxious or flat can make a phone attractive, and heavy use may then leave you more tired and more strained, which could make the original feeling worse. That is an observation, not a research finding, and loops like this can be entered from either side.
This matters for how you read yourself. If you reach for the phone when you feel low, that is a very ordinary response to a hard feeling, not a character flaw. And the trial evidence suggests that cutting back on phone internet can help.
What can you do with this?
- Treat the phone as one lever, not the whole picture. If low mood or anxiety is persistent or heavy, it deserves proper support from a doctor or therapist, whatever your screen time looks like.
- Consider protecting sleep. Sleep was one mechanism in the trial, and screen time is linked to later bedtimes. Charging the phone outside the bedroom is a simple, free way to try it.
- Try a limited trial. The study that worked used two weeks. You could do something similar with the apps that leave you feeling worst, and see what you notice about mood and focus.
- Notice the order. For a few days, jot down whether you felt bad before you picked the phone up or after. That tells you more about your own loop than any study can.
- Expect the first days to feel odd. That is a guess from experience rather than a research finding, so go easy on yourself if it does.
If you want something to hold the line, Boredom blocks the apps and puts a short guided reset in the gap. You do not need an app for any of this, though.
The short version
Heavy short-form video use is linked to more stress and anxiety, and one survey linked "brain rot" (cognitive fatigue) to depression indirectly, via burnout. Most of the evidence is correlational, so it cannot say that phones cause depression on their own.
What we do have is a randomised trial in which two weeks without mobile internet improved mental health, well-being and attention. If your phone use and your mood are tangled together, loosening the phone end is a reasonable, low-risk experiment, and it is not a verdict on you either way.