What do we really know about the effects of screen time on mental health?
Public Health England this week
announced that too much time in
front of TV and computer screens
is causing increasing psychological
problems, such as depression and
anxiety, in children. The report,
which can be found here, suggests
that the amount of time spent
playing computer games was
negatively associated with
wellbeing in children – in other
words, their general mental and
physical health, resilience and the
extent to which they are happy or
worry about different aspects of
their lives. The effects, particularly
on mental health, were most
pronounced for those children who
spent more than four hours a day
using some sort of screen-based
technology.
While this sounds all doom and
gloom, there are some caveats that
need to be taken into account. The
briefing was released to coincide
with the Change4life campaign,
and isn't a piece of peer-reviewed,
scientific research. In its discussion
of screen time, it cites data from
other reports, for example,
commissioned for the Department
of Health that are themselves
secondary analyses of existing data
sets, such as the Millennium Cohort
Study . If you have a read of these
reports, it's really difficult to get a
sense of what they did and didn't
control for in looking at the effects
of playing video games or watching
TV.
But it's worth pointing out that the
PHE briefing starts off with a very
clear outline of the limitations of
their research – perhaps the most
important being that it's not
possible to establish causal links
from most of the studies involved.
In other words, when a study says
that 'X is associated with Y', it
doesn't mean that 'X causes Y',
which is how it can often be
interpreted. It could also mean 'Y
causes X', or maybe some other
factor is having an effect on both.
So it's a shame when you see
headlines such as the Independent's
"Overload of screen time causes
depression in children" , or the
Daily Mail's "TV is making children
unhappy" – the study didn't say
anything like this at all.
But what do we actually know
about the effects of screen time on
childhood development? It's
actually a really tough question to
answer, in part because "screen
time" is a pretty rubbish concept. It
takes into account the use of
anything that has a screen – TVs,
mobile phones, games consoles and
tablets. In a sense, it's easy to see
how it's a compelling measure to
use: it's a simple idea that everyone
can easily relate to. The trouble is,
it doesn't really do justice to the
sheer diversity of content that
screen-based technology can
provide. For instance, two hours of
watching Teletubbies is probably
going to affect our behavior in a
completely different way to
playing Halo for a couple of hours
(although it's questionable which
one will do the more damage).
With this issue in mind, what does
recent scientific evidence in this
area look like? In March,
researchers at the Public Health
Sciences Unit in Glasgow published
data that also came from the
Millennium Cohort Study (although
it wasn't cited in the PHE briefing),
which looked at whether watching
TV or playing video games at aged
5 was associated with behavioural
or psychological problems at age 7.
They controlled for a large number
of factors that could potentially
impact on their results – things like
health, family socioeconomic
status, frequency of parent-child
activities, and a measure of chaos
in the household.
The results showed that when
considering screen time on its own,
there were associations between the
amount of time spent at a screen
and all of the problems they looked
at – hyperactivity, conduct
disorder, peer relationship
problems, and so on. However,
these associations all but
disappeared once the confounding
factors mentioned above were
included. The remaining
significant association was between
viewing TV for more than three
hours per day and conduct
disorder.
Obviously, one study doesn't tell
the whole story – for instance, we
know that the amount of time spent
watching TV is linked to poorer
physical health. But we also know
that there is – or should be – a
distinction between passive and
active screen time. Along these
lines, a systematic review from
2010 pointed out that active video
games actually promote light-to-
moderate physical activity in
children.
As it stands though, research into
the long-term effects of screen time
is still relatively young, so we don't
yet know what effects playing
video games, using computers, or
watching TV has on childhood
development.
In releasing the briefing alongside
the change4life campaign, the PHE
is trying to encourage people to
take up a more active lifestyle,
swapping the car for bikes or
walking, limiting screen time and
cutting down on unhealthy snacks
in favour of healthier foods. These
are all great ideas, but it seems that
the best way to stay healthy is to
change all of these things, not just
one.
In the same way, we must be wary
of looking at the effects of screen
time in isolation from the myriad
factors in the wider home
environment that could be
impacting on childhood
behavioural development.
