Just one more episode – four reasons why binge watching is bad for you

Sedentary behaviour expert, Sophie Carter, explains why binge watching TV is detrimental to your health.

There’s a treadmill waiting for you at the gym but the glow of the TV is so inviting as the rain offensively hits your window pane. You sit down for just a minute and before you know it several hours have passed, your eyes are heavy – "just need to make it to the end of this series" you tell an empty room, everyone else having long ago departed sensibly to bed.

Sound familiar? As the cold, dark nights approach many of us will retreat into something like a semi-hibernation: curled up on the couch, snacks at hand, ready for a session of binge watching the latest series of our favourite programme. And, of course, we know all this sitting around is bad for us, but how bad is it?

We caught up with Sophie Carter who recently finished her PhD within the School of Sport and Exercise Sciences investigating the effects of sedentary behaviour on brain blood flow and cognitive performance. We asked her to explain just why binge watching is detrimental to our health.

1. It can shorten your lifespan

"A study showed that each one hour increase in TV watching was associated with an 11% risk of all-cause mortality. However, it has been suggested that, participating in at least one hour per day of moderate-intensity physical activity can prevent this risk. Given that most people struggle to achieve the guidelines of 30 minutes of moderate-intensity activity five times a week, an hour per day is highly unachievable. This means that the majority of people who sit for prolonged periods of time will have a reduced lifespan as a result. Due to the barriers individuals face which stops them participating in physical activity, reducing the time they spend sitting could be a more feasible option to decrease this mortality risk."

2. It can affect your mental health

"Some studies have shown that watching TV is associated with depression and anxiety. However, this research cannot determine whether watching TV led to mental health problems or the other way around."

3. It may lead to diabetes

Prolonged periods of sitting has a negative effect on how we control our blood sugar levels – putting junk food into the mix makes things worse, as Sophie explains:

"Research has shown that after consuming a high sugar meal or drink, if a person then sits for a long period, their blood sugar levels are higher and stay higher for longer. Therefore, if individuals are sitting for prolonged periods watching TV and combining this with eating high sugar snacks, a similar scenario may occur. Importantly, in the long term, poor control of the levels of sugar in the blood can lead to diabetes."

The good news though is if you break up your sitting time with activity, your blood sugar levels are lower and return to normal faster.

4. It can increase your chance of developing blood clots

You’ve probably heard about how travelling by plane can increase the risk of developing blood clots due to long periods of immobility. Not unique to plane travel, this condition can be caused by any lengthy period of sitting. Sophie describes the research that has been done around deep vein thrombosis:

"A study assessed the effects of uninterrupted sitting for seven hours on markers in the blood that can lead to the formation of blood clots. They found that following sitting, the levels of fibrogen, a protein that is involved in the formation of blood clots, was increased. However, the study showed that breaking up this sitting time with two-minute light-intensity walking breaks every twenty minutes prevented this increase. The message from this study and that of many others assessing the effects of prolonged sitting, is that we need to sit less and move more, more often."

Sophie now works as a senior lecturer in the School of Sport at York St John University. For her PhD at LJMU she looked into the sedentary behaviour of office workers along with fellow researchers in the School of Sport and Exercise Sciences. The study showed that after four hours of sitting there was an acute reduction in blood flow in the brain. However, when sitting time was interrupted every 30 minutes with a two-minute walk, this prevented the decline in blood flow. Walking every two hours did not prevent a brain blood flow reduction. So, the advice is: take frequent breaks while sitting at your desk. While Sophie’s research didn’t specifically explore the effects of sitting while watching TV, Sophie believes it’s possible that a similar effect could occur but further research would need to be conducted to examine this in more detail.

Read the New York Times article about this study.

If you’re interested in studying sport science, the School of Sport and Exercise Sciences has been ranked the ninth best department in the world according to ShanghaiRanking, so why not take a look at the courses on offer? 

Did you know LJMU students get free gym access to help them keep fit and healthy throughout the year? It’s just one of the benefits of being a student at Liverpool John Moores University. 

Do you have a question you’d like to ask a scientist? Send us your question and we’ll try to get the answer.