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"Going to work" at 9am could mean "going to do work" at 9am. But it could also mean "going to an office at 9am to drink coffee and watch clips of late-night hosts skewering Trump for half the morning, before easing into job tasks at 10:45am." 

In a similar manner, "going to bed" and "going to sleep" are two related but non-synonymous concepts that, thanks to our modern-day technology habits, are only becoming more distant. "Going to bed," in our screen-addled era, may very well mean getting under the covers to stream "Tiny House Hunters." (I'm not finger-wagging; I've logged plenty of hours in bed squinting at my cracked iPhone screen.)

And two researchers from The University of Michigan and KU Leuven in Belgium, Jan Van den Bulck and Liese Exelmans, argue that the existing concepts in sleep science don't account for the way electronic media has become woven into our bedtime-and-sleep regimens. It's not that sleep studies don't acknowledge the lag time between crawling into bed and drifting off to sleep. They do, which is why there's so much data on sleep latency, meaning the amount of time between going to bed and falling asleep. But Van den Bulck and Exelmans don't think sleep latency tells the whole story of our pre-and-post bedtime routines. 

"Until recently, sleep latency mainly implied the time it takes to fall asleep after having gone to bed," they wrote, in a 2015 editorial published in Behavioral Sleep Medicine. '"In the electronic media age, people may go to bed with or without the intention to go to sleep. Different definitions are therefore needed for “the time between going to bed and falling asleep” and “the time between ceasing all activities in bed and falling asleep.”'

Basically, there's now an extra chunk of in-bed leisure time that studies are glossing over. So, to reflect the fact that our bedtime timelines are a-changing, Van den Bulck and Exelmens propose both re-defining sleep latency and adding a new term, shuteye latency, into the mix. Here's a rundown of the terms:  

Bedtime: when you decide to go to bed
Shuteye time: when you decide to fall asleep
Actual sleep: when you actually fall asleep
Old definition of sleep latency: the gap between bedtime and acutal sleep
New definition of sleep latency: the gap between shuteye time and actual sleep
Shuteye latency: the gap between bedtime and shuteye time 

Equipped with their revised lingo, the duo studied bedtime electronic media use and published their findings last month in the Journal of Sleep Research. For the study, 338 Belgian young adults, recruited through Facebook, assessed their bedtime and sleep habits, sleep quality and electronic media use (meaning all device-dependent activities). In addition to using well-established sleep questionnaires, researchers designed a new scale to gain a more nuanced understanding of bedtimes, shuteye times and the activities surrounding them. 

On average, researchers found, participants went to bed around midnight and reported a shuteye latency (the gap between deciding to go to bed and deciding to go to sleep) of 39 minutes. What were participants doing before and after hitting the sack?

Before bed, they were most likely on their phones or laptops. Pre-bed electronic media use took up an average of nearly 18 hours a week. As for pre-shuteye activities (what you do after climbing into bed but before you decide to go to sleep), participants spent the most time on non-media activities, meaning personal hobbies, sex and social activities (like talking IRL or on the phone). That's not to say they steered clear of electronic media entirely — pre-shuteye, they averaged 3 hours and 41 minutes of weekly e-media use, predominantly spent on phones and laptops.

It might make sense for a study to include a shuteye-latency question, such as: "After going to bed, how long are you awake (doing things other than sleeping) before trying to sleep?"

But, regardless of how participants filled their pre-shuteye time, researchers found a connection between more pre-bedtime e-media use and longer shuteye latency. In other words, participants who spent more time with e-media before bedtime subsequently stayed up longer (doing whatever) before deciding to go to sleep. 

And, as researchers predicted, longer shuteye latency was associated with poorer sleep quality; those whose shuteye latency exceeded an hour were over nine times more likely than other participants to have sleep issues. In general, men came across as more cavalier about going to bed, going to sleep and indulging in late-night screentime. 

Why, exactly, does this all matter? Well, according to Van den Bulck and Exelmans, studies need to delineate between bedtime and shuteye time clearly so they don't produce flawed data. In the current study, for instance, sleep latency exceeded 30 minutes for almost half of study participants. Using standard sleep measures, these participants would be classified as having sleep-onset insomnia. The problem here is that insomnia would only be an appropriate diagnosis if participants spent that half hour actually trying to fall asleep. But, as the current study showed, they were using that time in bed to do things besides sleep. To prevent an error like that, it might make sense for a study to include a shuteye-latency question, such as: "After going to bed, how long are you awake (doing things other than sleeping) before trying to sleep?"

Researchers also point out that sleep hygiene guidelines mainly focus on what people do before going to bed. It's time, they suggest, to include best practices for post-bedtime behavior. A new rule might be something like: "'In order to avoid electronic media use after lights out, users should create a bedtime for their electronic media: Lights out should become synonymous for “media out,” a simple enough message."'