Binge-watching television shows before bed leaves viewers in a 'zombie-like' state, reduces sleep quality and increases the risks of increased fatigue and even insomnia.
This is the conclusion of a study into binge-watching by the University of Michigan and the Leuven School for Mass Communication Research in Belgium.
Having surveyed 423 young adults between the ages of 18 and 25 in February 2016, researchers found that those who binge-watched TV in the evening reported more fatigue and lower quality of sleep.
It was found that these factors remained even if the participants got the recommended seven to nine hours each night.
Watching several TV episodes before bed left their brains in a highly engaged state, making it difficult to switch off, fall asleep and sleep deeply. Those who slept badly would catch up by sleeping-in the next day.
Study co-author Jan Van den Bulck said: "Our study signals that binge viewing is prevalent in young adults and that it may be harmful to their sleep."
Of the 423 adults surveyed, 80% said they had binge-watched during the previous month. 7% said they binge-watched every day. Men binge-watched less frequently than women, but their TV-watching sessions were twice as long.
The findings have been published in a report by the University of Michigan, titled 'Binge-watching The Walking Dead? You might feel like a zombie yourself.
The report states: "The study showed that increased cognitive arousal prior to sleep (i.e. being mentally alert) is the mechanism explaining the effects of binge viewing on sleep quality... A racing heart, or one that beats irregularly, and being mentally alert can create arousal (or pre-sleep arousal) when a person tries to fall asleep. This can lead to poor sleep quality after binge-watching."
This heightened state of alertness, Liese Exelmans of Leuven School says, "prolongs sleep onset [and]... requires a longer period to 'cool down' before going to sleep, thus affecting sleep overall."
With streaming services like Netflix offering up the next episode of a program the moment the last one finishes, binge-viewers might not even realise the state of their viewing habits, the report adds.
Exelmans concludes: "Basically, sleep is the fuel your body needs to keep functioning properly. Based on that research, it's very important to document the risk factors for poor sleep. Our research suggests that binge viewing could be one of these risk factors."