The third variable that I will be manipulating across a two week period to examine its impact on sleep is TV – specifically watching it in the last two hours before bedtime.
I will discuss what my data shows, how easy or difficult I found this strategy to implement, and what previous research says. These three factors will be combined for an overall score and grade on how useful avoiding TV before bedtime is at helping people to improve their sleep.
TV or bright screen usage is not something that I have been keeping track of this year, but the reason I want to study it is that I know that:
- A lot of people watch TV in the last two hours before bedtime.
- A lot of my clients say that it helps them to wind down before bedtime.
- I do not recommend using bright screens in the last two hours before bed.
I generally don’t include the TV in with other bright screen use, as computers, tablets and phones are usually closer to people’s eyes and therefore their light receptors than a TV is. It might still be having an impact, especially with how big some TVs are these days.
I also know that people who like to watch TV before bed probably aren’t going to stop this, especially if it has become a long engrained pattern. Surely we should see if it has a significant adverse impact on sleep before recommending that it needs to be cut out alongside the computer, tablet or phone usage.
To explore the impact of TV on sleep, I decided to once again be a little bit more extreme than I usually am.
For the first week I watched:
- One hour of TV before bed on Sunday and Wednesday
- One and a half hours of TV before bed on Tuesday and Friday
- Two hours of TV before bed on Monday, Thursday and Saturday
For the second week, if I watched any TV, it had to wrap up at least 2 hours before bed. What this meant is that I had to be creative with what else I could do before bed that didn’t involve bright screens. This meant talking to my partner more, journalling, reading or meditating.
If you decide to try this at home and switch off your TV in the two hours before bed, just focus on doing something that isn’t too physically demanding or emotionally intense, as the key is to try to relax and lower your arousal levels, and then go to bed once you feel sleepy.
Other ideas that don’t involve bright screen time include playing board games or card games, playing a musical instrument or listening to music, colouring, drawing, painting, knitting, cross-stitching or any other hobby really.
Comparison 1: No TV vs baseline data
With no TV in the last two hours before bed, my sleep efficiency was at 96.84%, 0.64% higher than the baseline data, but not as high as the no alcohol data and just below the no caffeine data. If you take out the Friday where I caught up with old friends and Saturday night where I went to a wedding, this increases to 97.7%, higher than no caffeine, but still not better than the week where I had no alcohol.
My time to get to sleep was nearly 2 minutes longer than baseline, but my time awake during the night was half of what it was during the baseline period, with awakenings only being recalled on the two nights that I’d consumed alcohol. My bedtime was still 17 minutes later than at baseline, but was earlier than all of the caffeine and alcohol data, and is positively trending in the right direction again. My time in bed was 2 minutes less than baseline, and I was getting out of bed 15 minutes later in the mornings.
My sleep quality was rated as a 4.29, equal to caffeine, better than alcohol and no caffeine, but not as good as the no alcohol data. Take out the last two nights where I did drink alcohol, and my sleep quality with no TV rises to a 4.8 – the best rating so far!
Objectively, There were 3 nights where my sleep had a restful: light sleep ratio of more than 2:1, which is excellent. The Feb 21 Misfit data (20/2/17 on the sleep diary) was the best, with a substantial block of deep sleep and a ratio of 2.15:1.
The worst sleep was the Friday night, with a ratio of 0.75:1. More evidence that alcohol has a tremendous impact on objective sleep quality!
Comparison 2: TV vs No TV
Looking at the sleep diary data, I woke up 0.28 fewer times per night when I didn’t watch TV than when I did, went to bed 12 minutes earlier, fell asleep 3.57 min quicker, awoke for 1.43 minutes less, and had better sleep efficiency and subjective sleep quality.
I did sleep 7 minutes more per night on the week that I watched TV, but I was within the recommended 7-8 hours of sleep on both weeks.
I also spent 12 minutes less in bed and was able to get out of bed 24 minutes earlier in the week when I didn’t watch TV before bed.
By remaining away from the TV and other bright screens in that last two hours before sleep, my body clock (or circadian rhythm) really did seem to start to shift forward to an earlier sleep and rise time, which is really important for someone like me with a tendency towards having a delayed circadian phase.
Objectively, even with watching 2 hours of TV before sleep my sleep wasn’t too bad. Like the no TV week, my worst night of sleep objectively was on Feb 18 (17/2/17 on the sleep diary), where I caught up with some volleyball friends for dinner and had some alcoholic drinks. My restful: light sleep ratio was 0.97:1 on this night – better than when I avoided TV the week after.
My best sleep objectively was Feb 13 (12/2/17 on the sleep diary), where I watched 1 hour of TV before bed. The restful: light sleep ratio on this night of 2.14:1 was nearly as good as my best night of the week with no TV. The 6 hours and 13 minutes of restful sleep that I obtained on this night were the most that I have had on any night this year!
IS AVOIDING TV BEFORE BED A GOOD SLEEP STRATEGY?
For me, yes. Not as useful as avoiding alcohol, but better than avoiding caffeine. It beat watching TV before bed on 7 out of the 9 categories that I measured on the sleep diary, so I give the effectiveness of this strategy a 19/25.
For me, not watching TV was fun, as the other things that I did instead are more in line with my values and who I’d like to be, especially socializing, meditating and reading regularly. Journaling is good too, but I generally don’t recommend doing this in the last two hours before bed either for the challenging emotions that it may bring up at times.
For others, especially if their housemate or partner really enjoys watching TV together with them, I imagine that it would be a lot harder. I give the applicability of this strategy a 17/25, as I’m not saying that you have to stop watching TV altogether. Just not in the last two hours before you go to sleep.
Data from Project Viva has found that for every 1 hour of increased TV viewing per day, a child’s sleep decreased by 7 minutes each night. Having a TV in their bedroom was even worse, and was associated with 8-31 minutes of less sleep per night (Cespedes et al., 2014).
Data from the GECKO Drench cohort has supported these findings and found that more televisions at home or in the bedroom led to more television watching for children, which was significantly associated with reduced sleep duration and higher BMI (Sijtsma, Koller, Sauer & Corpeleijn, 2015).
A systematic review by Hale and Guan (2015) found 67 studies that looked at the relationship between screen time and sleep in children and adolescents and found adverse sleep consequences in 90% of the studies. They did say that a causal link is not yet confirmed but recommended that we:
limit or reduce screen time exposure, especially before or during bedtime hours to minimise any harmful effects of screen time on sleep and well-being
— Hale and Guan (2015).
I’m still not sure if TV is less problematic than other bright screen use where the screens are closer to the eyes, but McIntyre and colleagues (1989) did find that more intense light exposure led to a higher suppression of melatonin. 1 hour of light exposure at midnight suppressed melatonin by 71% with 3,000 lux, 67% with 1,000 lux, 44% with 500 lux, 38% with 350 lux, and 16% with 200 lux (McIntyre, Norman, Burrows & Armstrong, 1989).
If you can download a lux meter app and then look at what it says where you usually sit to watch TV, it might give you an estimate of how problematic the behaviour is. Using the LightMeter App, sitting in my office with the lights on is 98 lux, and looking at the computer is 1287 lux. The TV reading would probably be somewhere in between.
I therefore give the science of this strategy a 33/50.
Overall, avoiding watching TV in the two hours before bed as a way to sleep better gets a score of 19/25 + 17/25 + 33/50 =
Watching TV for the 1-2 hours before going to sleep did mean that I went to bed later, took longer to fall asleep, woke up more during the night, spent more time awake during the night, and got out of bed later in the morning.
By avoiding TV and other bright screens in the last 2 hours, I was able to engage in other more beneficial activities that helped to reduce my arousal levels more. I also obtained 3 nights of sleep that objectively had a restful: light sleep ratio of more than 2:1 for the first time this year. It also seemed to help bring my body clock forward a bit, so that I was feeling sleepy earlier, getting to bed earlier and getting up at a more desirable time in the morning, which helped me to do more exercise before work and be more active during the day.
WHAT I RECOMMEND
I know that TV is enjoyable to watch for many people, but some data suggests that the more we watch, the less sleep we get. If you really want to watch your favourite show and it is within 2 hours of going to bed, go for it, just try not to make it a nightly habit. It would be even better if you could record your favourite late night programs and then watch them earlier the next day – that way you’d know that it won’t impact your sleep.
The 2016 Sleep Healthy Survey of Australian Adults showed that our sleep problems are 5-10% worse than they were in 2010, with 33 to 45% not sleeping enough or sleeping poorly. Of the 44% who surf the internet just before bed every night, the percentage of people having sleep difficulties climbs to nearly 60%.
Reading, meditation and even listening to music all have studies supporting their efficacy in reducing stress levels more than what watching TV does, and they all have the added benefit of not including bright light. Removing TV from bedrooms and pre-sleep routines are unlikely to be harmful and could be beneficial.
If you have sleep problems and watch TV before bed, it’s definitely a variable that is worth experimenting with. Try watching your average amount of TV one week, then switch it off in the last two hours the next week, and see what it does for you.
If nothing, at least you know that you don’t have to feel bad about watching TV pre-bed. If it is having an impact, surely it’s worth switching it off a bit earlier if it means better sleep for you and all of the other benefits that come with this.
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