Alertness associated with last night’s sleep, physical activity and food intake | Hacker News Reader

Alertness associated with last night’s sleep, physical activity and food intake

nature.com

186 pointsPaulHoule47 comments

I was actually a bit surprised by the low regression coefficient values in figure 3. To me, the low values say that many of those features are not hugely important. The authors don’t emphasize this, but they also found that going to sleep later correlated with higher morning alertness.

My own takeaway from the data is a bit different from what the authors say conversationally (vs in the figures). I’d summarize the paper, mostly based on figure 5b, as:

Try to be happy, old, sleep well, and don’t eat too frequently.

In terms of breakfast, the data’s main conclusions are to avoid a lot of sugar (which is hugely important), and to wait a while before eating breakfast (see fig 3).

they also found that going to sleep later correlated with higher morning alertness

I always found this to be true for myself--if I got 6 hours of sleep I'd be much more alert in the morning than if I got 8.

Same here. But I always associated it with stress.

I feel the same way but after wearing a heart rate monitor, it definitely detects a higher daily average heart rate so it can't be healthy.

Normal days: 50-55bpm

Low sleep days: 63-68bpm

I've noticed similar. I've woken up early, taken my pulse and notice it was a bit high and used that to decide to go back to sleep.

I've always feel like I get my best quality sleep when I go to bed extremely tired.

This could have to do with whether you're waking up in between versus in the middle of a sleep cycle. From what I understand, the former is preferable to the latter.

Well, it is "morning alertness", from what I've observed on myself "bad" (whether short or interrupted) sleep have far higher negative impact on rest of the day than morning.

To me it's the exact opposite. I usually end up feeling much better later in the day if I can't sleep but mornings are absolutely brutal. Even if I sleep well, I feel a bit groggy in early mornings; if I didn't sleep well I'm a complete zombie, but later in the day I will feel better, hopefully.

Same here

These sound like perhaps conditions that CPAP would help?

I'm personally disappointed by their lack of awareness of how weakly related subjective sleep quality is to polysomnographic variables.

A few things I have found work well for maintaining energy levels and maximizing productivity levels throughout the day.

1. Only eat foods high in carbohydrates around the time you exercise. (Reduce carbohydrates on days that you don't exercise)

2. Workout in the morning or afternoon (ideally afternoon). (Working out at night will disrupt sleep and I have found that working out in the morning slightly decreases energy levels in the afternoon compared to working out in the afternoon.)

3. Avoid eating 6+ hours before going to bed.

4. Try to do some light exercise (walking/stretching) after you eat.

5. Make sure you're consistently drinking water throughout the day (a little bit less around the times you eat).

6. Only go to bed when you're like 8+/10 tired (time asleep doesn't matter much if the quality is slow)

7. Avoid screen time at least 1 hour before bed (this is basically a must to achieving 6...)

8. Wake up (get up) when you wake up relatively alert or when you have to get up. If you always stay in bed until you have to get up then you're probably not aligning your waking time with your sleep cycle which means you'll be more tired throughout the rest of the day

There are actually a lot of other things that I think help as well (diet, meditation, etc...) but I didn't want to make this post any longer than it is.

Lastly, I just wanted to say that having sleep aligned is SO important because it improves our energy/emotional state which ultimately assists us with other productive activities. (it's really a productivity multiplier)

Associating all these health markers (sleep, activity, diet) with an actual result is cool and something more fitness apps should do. Right now you can setup tracking for all these things relatively easy but the purpose of tracking them seems to be vaguely feeling "good" or losing weight. The apps encourage you to sleep a certain amount and exercise but it seems difficult to correlate those numbers with performing something you care about at a higher level.

I usually just say something like "yeah I guess I have been feeling more focused lately" but that seems pretty subjective.

>seems pretty subjective.

The gold standard of medical evidence is the clinical endpoint. How someone feels after receiving treatment is subjective, but is is subjective per subject, so the subject in the numerator cancels with the one in the denominator, and the result is an objective measurement.

There are so many instances of people feeling they are doing well when the objective measure reveals that they are not. The Dunning Kruger effect became a meme because people are so bad at objectively measuring their own performance.

It is philosophical whether feeling you are doing good is more important than actually doing well, but for a metrics based study like the one this thread is based around I want objective measurements.

Can recommend http://intervals.icu

Request it, it may get done.

Interesting. Anecdotally, I do feel way sharper, eloquent and wittier when I am on low-carb, fasting-often-and-long diet I practice between September and March. I tend to feel sleepy and bloated on a high carb diet I do most of the summer (and that's not sweets or soda, it's just adding bread and pasta). I do a lot of fasted cardio, including things like cycling 200km during a 36hr or 72hr fast. I do software design for a living, so generally have to think hard with some regularity :-)

As a 200km+ cyclist, at what times of the day do you eat? Eu or US based?

Interested, as i've never tried seasonal variations, as opposed to daily/ weekly.

I do whack in the sugars, though pre-ride (day before) and then fast until finished, whatever the distance. Eating during, bloats me and i mentally just kinda give up.

Usually in the morning the next day. Rarely I do two day fasts-and-long rides, but I mainly did that to see how my body would reapond. I live in the Netherlands. I ride all year long.

I think it takes weeks to get used to fasted cardio, though. At least 2-3 weeks, and I eat keto on eating days when I do that, and I ride at a leisure pace of around 25km/h despite riding on an otherwise fast, light road bike. Anything truly intense kicks me out of ketosis and quickly drives me towards starving and loosing strength. I do different things in the summer as I love a beer and french fries when the weather is nice :-)

It makes sense that the average person would feel less alert without breakfast since they’re not used to low-carb.

I recommend every single person I know to screen themselves for Sleep Apnea -- My doctor estimates 30% of the population has it and most people go their whole lives without ever knowing.

Personally, my CPAP has boosted by daily energy/wakefulness tremendously, I feel at least 40% more energy each morning when I get a perfect CPAP adherence overnight, and I only had a minor/moderate case. If you snore, you probably have it without knowing.

Please get checked and make your life much better!

30% of the population do not have Apnea. Initial estimates in research were 3%, then a few years ago we started seeing numbers in the 8% to 12%. I have never seen a research paper that suggests anywhere near 30%, but that number gets batted around a bunch.

I'm not going to say Apnea isn't a problem. It is. I'm happy it made your life better.

If you snore, you do not "probably" have apnea.

Intermittent fasting has been life changing.

Only eating between 5-9 pm means a deep sleep from digestion of 2500 calories. Also, skipping lunch prevents the post lunch tiredness which would reduce my physical activity so I can more easily stay on my feet at least 12 hours a day.

I did that for long time, just one big meal in the evening, but over time I figured out that for me it works better to move it earlier (say noon) as it makes easier to fall asleep. Food before bed kinda does opposite for me, I stay longer than I want after.

It took a bunch of time to get used to longer breaks between meals but I can go for whole day without food without feeling all that much hunger. Dropping fast metabolizing foot also helped with that.

Only time where food makes me sleepy is if I had a lot after a period of average negative calorie intake, my body just goes "okay we sleep now" regardless of time of day.

Tom Rath's book "Eat, Move, Sleep" reinforces this same simple message. It seems like common sense to me, but for those who want the science, there you go.

This feels like "alertness associated with other positive health traits."

That is, I don't think most people or animals choose to lower their physical activity just because they can. Often lowering any of those is due to onset of sickness and you can observe this in pets.

Reading over the above, I do want to underline that this is still worth studying. I just hate that the reporting on it is painting a one-way causal link.

I also think the amount of psychological tricks that are employed against people is absurdly high. Such that the reasons we overeat or just eat the wrong things are as likely not about cravings you would have absent the effort companies put into giving you these cravings.

> This feels like "alertness associated with other positive health traits."

Going to bed later was also associated with alertness.

Ah, good point. For that, I would simply rephrase that too much sleep is also bad. Which, is a less controversial way of framing it. And still fits with my generic framing.

Ah, the usual thing.

I can feel more focused and with increased alertness by fasting, avoiding sugar and taking plenty of stimulants.

Now what does this do to the suprarenal glands on the long term? What about TSH?

No one cares about that it seems. We feel "good", so it must be good.

Rest, exercise and nutrition are the pillars of health. No surprise there whatsoever. It is understandable that they have cognitive impact on alertness too. It is interesting therefore to see this connection explored.

Anecdotally this feels like “D’oh! Who would’ve thought your mind works better when it’s rested and fueled!?”

But it’s nice that someone did a science about it. Now can they someone figure out why as a person this finding is the last thing I think of when going through a day in a cranky fuzzy mood thinking “why the hell am I feeling this way!?”

However, this finding from the abstract caught my eye:

> a breakfast rich in carbohydrate, and a lower blood glucose response following breakfast

Not a nutritionist, but based on all the other stuff I’ve read, how does high carb + low glucose work together? Doesn’t high carb lead to high glucose response?

You can select carbohydrates with a low glycemic index (meaning that your blood sugar rises more slowly). For example, oatmeal has a glycemic index of 55, and pure glucose has a glycemic index of 100, meaning oatmeal spikes your blood sugar only 55% as much. This is true even for two items with identical calories.

This and the other food you're eating with the carbs, like the amount of fat and fiber.

The glucose reponse depends on your ability to process the carbs.

My take is that carbs are good for fueling performance but I've also had the experience of losing significant weight with a high-protein diet and putting on muscle mass. I schedule exercise around my ability to digest: on a totally empty stomach I can do very little, but a full stomach demands energy to digest and can lead to vomiting, fainting, etc.

I would like to practice intermittent fasting but what I find when I don't eat at all in the evening is that I can lay in bed all night and not sleep a wink.

Long distance running helped me with this. Don’t know if it’s the running itself or the metabolism training that comes with it.

When you burn 3000+ calories in 4 hours, that’s like sped up fasting. No way to eat that much. So you learn to function and perform while hungry.

Most people that practice intermittent fasting eat their meal in the evening so that they can go to bed well fed. This allows your body to rest and digest at the same time. The fasting window is from your last meal until mid day the following day.

My take on IF is to skip 'breakfast', and allow myself to eat between lunchtime and late evening.

Sleeping means I'm not eating, and no morning meal saves me a few minutes of time and effort. It also means that it's easier for me to not screw up my IF if I want to go out to eat with people, since few are interested in dining out early in the day.

Working out midday before lunch is a new challenge for me, and I'm still getting into the hang of it, as opposed to after work hours. I still start yawning whenever I get to the gym, and I definitely don't have the same amount of performance, but I'm trying to get myself into it.

> Working out midday before lunch is a new challenge for me, and I'm still getting into the hang of it, as opposed to after work hours.

For me, once I got over the initial hump, my workouts before my first feeding are great. I have tons of energy, and am just ready to go. That initial hump was a little rough as I used to eat breakfast as soon as I got up. Now, I only start to notice real hunger if I skip breakfast and lunch.

I have more 'work' to do in figuring out where my pre-gym yawning comes from, but tend to have my burst of clarity/energy once I'm done. Maybe it has something to do with sitting for so long? Not sure yet.

I do pretty much one meal a day (second "meal" being cocoa or coffe with milk in the morning) but it took slowly cutting meals over time + eating more filling and slower digesting stuff overall.

Like replacing egg + toast with egg + some diced potatoes and onion pan-fried with the egg will probably keep you sated for longer.

Now the hunger comes in slowly and generally I feel a tiny bit of hunger when I fall asleep, wake up hungry, get my glass of milky drink for the "breakfast" to keep hunger at bay for next 2-3 hours, then get/cook something for dinner.

> how does high carb + low glucose work together?

Not always, but typically, higher-fiber carbs don't spike your blood glucose as much.

Practically, this means having steel cut oatmeal for breakfast instead of Cheerios. Prepare them savory instead of sweet, like you might with grits.

Steel cut oatmeal + an egg + 1tbsp cottage cheese + hot sauce is an amazing breakfast

> Steel cut oatmeal + an egg + 1tbsp cottage cheese + hot sauce is an amazing breakfast

I don't eat breakfast b/c of IF, but damn, this made me hungry.

Oatmeal + peanut butter + fruit (blueberries, strawberries, kiwi, banana, or raisins if you happen to run out of fresh fruit) is a good option too. The fruit has sugar, but not much, and anyway has fiber and vitamins to balance things out.

I used to think the same thing, but tried a continuous glucose monitor. I found out steel cut oats were actually really bad for my glucose levels, spiking them into unhealthy levels around 160. More than whole wheat bread and other carbs.

Obviously this is highly subjective from person to person however reading other anecdotal evidence from people who have used a CGM, it’s pretty common.

In other words don’t assume it’s a low glycemic food because the internet says it is.

Related: anecdotally, morning sunlight really improves my overall sleep. Learned about it here:

https://hubermanlab.com/sleep-toolkit-tools-for-optimizing-s...

> Let your food be thy medicine - Hippocrates

> It is vain for you to rise early and put off your rest at night - psalms 127:2

> To be idle is a short road to death... - Buddha

Things that have been known since... Well, forever

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