#70 - Are National Geographic's Sleep Tips Credible? - PART 2
‘Sleep Tips’ are scattered all across the internet.
The media love them!
There’s been so many journalists who have interviewed me and then ask “What 5 Sleep Tips can we provide for our readers?”.
I use to answer this question. Now I don’t.
The people who want a Sleep Tip are the ones that need tailored advice. Or at least some quick evidence-based sleep tip (ie, one that works) from someone credible.
We love National Geographic - a credible organisation.
So when they released their special issue on ‘Sleep’, we noticed they included their Top 10 Sleep Tips.
Are Nat Geo’s Sleep Tips Credible?
We reviewed the first 5 Sleep Tips earlier - so it’s about time we took this to the finish line and review their Final 5 Sleep Tips.
Here we go!
Sleep Tip #6: Don’t Eat A Large Or Spicy Meal
“Big meals can bring on indigestion”.
Eating a meal increases metabolism. It ‘burns’ the energy from the meal, and as a result there is an increase in our core body temperature. If we eat a large meal, then this can be pronounced - like the figure below when Subject #15 ate a 1600 kcal meal at 10:00 PM compared to his peer (Subject #7):
The red arrow shows that Subject #15’s temperature rose at a time when it would naturally decline and remain low - like it did for Subject #7. Regardless, eating a large meal caused increased sleepiness in this study. Indeed, other studies have found large meals increase our internal body temperature (which should make us more alert) - but no effect on sleep has been found.
In contrast, a spicy meal can also increase body temperature, but only have an effect on sleep at the start of the night (eg, less deep sleep).
Even so, it’s not crystal clear whether this alteration of sleep at the start of the night is noticeable the next day - aside from having a burny bum when going to the toilet.
So perhaps the best advice is to avoid large meals and/or spicy meals if you are really hot at night when you try to fall asleep - or when the air temperature in the bedroom is really warm (as this will make it hard for the heat to escape your body at night)?
Sleep Tip #7: Exercise Regularly
“Fit people sleep better, but workouts within an hour before bedtime can make you too invigorated to drop off”
Simply put - it’s true that regular exercise is related to better sleep (Kredlow et al., 2015).
When I began treating people with insomnia back in the 2000s, the rule of thumb was to avoid exercising within 3 hours of going to bed. The reason was that exercise increases our core body temperature, which in turn increases alertness.
But - new evidence shows that exercising within the 3 hours before bed can have little-to-beneficial effects on sleep!
As for workouts within 1 hour of going to bed? The evidence is there , but it’s not compelling (Stutz et al., 2019)
And if the data we’re currently crunching stays true, then it’s not the intensity of the exercise before bed that affects sleep, it’s whether you’re completely sedentary in the 3 hrs before bed (which may just be one indicator of a generally unhealthy lifestyle).
Sleep Tip #8: Expose Yourself to Bright Light
“… in the mornings to set your body clock. Then avoid bright lights and the glow from electronic devices for at least 30 minutes before you intend to go to sleep.”
Nat Geo mean ‘expose your eyes’ to bright light (not flash the neighbours first thing in the morning).
Now for ‘entrained’ people (ie, those whose circadian rhythm is not heavily influencing their sleep) - then yes, this is true. The length of our body clock (24.19 hrs) doesn’t quite fit into the 24.0 hr day. If we did not expose our eyes to the resetting effects of bright morning light, then our sleep would gradually drift later and later each day.
For those whose sleep timing is affected by their circadian rhythm - like teenagers - they need an individualised plan. Getting up at the same time of day and exposing their eyes to bright light would be just as effective as getting up at the same time each day and flashing the neighbours.
As for the glow from electronics? Really Nat Geo? Even you? Start here to read about the science of this myth.
Sleep Tip #9: Keep Your Cool
“A bedroom temperature between 60-67 degrees Farenheit (15.5 to 19 degrees Celsius) tells your body it’s time to snooze.”
There really is a theme of ‘temperature’ in these last 5 Sleep Tips.
Nevertheless, let’s say it again. Your body temperature naturally cools to prepare you for sleep. It does this by releasing heat from various areas of the skin. Heat transfers from warmer areas to cooler areas, so it’s important that the air temperature around your body is much cooler than body temperature (eg, 37 degrees Celsius). Trust me on this …
I spent hundreds of hours in our Sleep Laboratory over the years, and the air temperature needed to be controlled. We usually set it to between 19-20 degrees Celsius. This seemed to be comfortable for people who slept in the lab - all year round.
But because people don’t usually sleep in labs, it’s their thermal perception that matters. And that can differ depending on where and when you live (Lan et al., 2017)
I struggle to find compelling evidence for such a cold bedroom environment (ie, 15.5 degrees Celsius).
Perhaps the Sleep Tip should be “If you feel hot, cool your bedroom. If you feel cold, warm your bedroom”?
But then again, these are Sleep Tips - not common sense.
Sleep Tip #10: Don’t Toss and Turn for Hours
“If you can’t sleep, get out of bed after 20 min, and do something restful in dim light. Then try sleeping again. Your extra efforts will be rewarded in a myriad of ways.”
The first two sentences are the first 2 steps of Stimulus Control Therapy (SCT).
SCT was developed by Richard ‘Dick’ Bootzin in the 1970s. He saw SCT being used for alcohol dependency and saw the potential for it to be used in the treatment of insomnia.
There’s a bit more to these instructions that the quote Nat Geo provided, so it’s a real shame they didn’t continue. Like “Repeat steps 1 and 2 until you fall asleep” and “Get up at the same time every morning” and “Avoid napping”.
SCT is considered to be a ‘Standard’ insomnia treatment component by a panel of experts, and is one of the components of CBT for insomnia.
It’s also a key ingredient in a less known therapy called Brief Behavioural Treatment for Insomnia (BBT-I).
I knew Dick Bootzin and had many conversations with him - including ways to modify SCT so people were more likely to adhere to it.
We teach this updated version of SCT in our new Online Certified Course - and it’s set at an Introductory Price for 2021.
Conclusion?
Nat Geo’s top 10 Sleep Tips were not bad. They weren’t spot on - but still, not bad.
Hopefully what this exercise has shown, is to do your own research.
Check if what someone is saying is true. Is there a published review of the literature, that summarises a bunch of studies, and makes a conclusion that supports what someone says.
This will help you discern the experts from the rest - and in the process, make you a sleep expert.
Prof Michael Gradisar