Dear Mark: The Linoleic Acid Content of Phosphatidylserine, and Optimal Sleeping Position/Location

For today’s edition of Dear Mark, we’ve got a two-parter. First up, what’s the deal with phosphatidylserine, one of the (most crucial) ingredients in Primal Calm? It’s a derivative of linoleic acid-rich oil, so what’s it doing in one of my supplements? Find out if you need to worry about undue levels of linoleic acid from taking Primal Calm. Then, are there any benefits to sleeping on one’s back as opposed to on one’s side? And how about sleeping outdoors under the stars and being woken up by the birds — is there any reliable reason that would improve the quality of our sleep and help us wake up more energized?

Let’s find out:

Dear Mark,

Thank you for creating Primal Calm – I’ve recently started using it and believe that I’ve experienced a marked boost to my overall wellbeing as a result. Having thus become a believer in the benefits of Phosphatidylserine supplementation, I’ve decided to make it a permanent addition to my life, but one thing worries me – given that all the “affordable” forms of PS are derived from plant sources, won’t I be pumping Linoleic Acid directly into my brain, and, in a highly bio-available form at that? I’d be happy to boost my dosage of krill oil instead… if it had any appreciable amounts of PS, that is.

My stress is sky high at the moment, and it’s not going to let up for a long time, so I need every advantage I can get. But I don’t want to embark on long-term and high dosage of a supplement without knowing the risks. In your opinion, is the amount of PS – even, say, 450mg a day (i.e., from 3 doses of Primal Calm a day) – too small to be concerned about in regard to the fatty acid profile, even if it is entirely from plant sources? I try not to worry about every possible risk, but, you know, my brain is kinda important to me 🙂



Whenever I make a product, I do it to address a deficit in my own life, diet, or coping capacity. Primal Calm was tailor made for the high stress individual, because, well, that’s me ten years ago. With the help of improved coping strategies, supplementation like Primal Calm, and a reconfiguring of my daily routines (I take less on my own shoulders and accept more help from my employees now), I’ve gotten stress and how I handle it to a manageable level. But back when I was developing Primal Calm? Man, oh man: I really, really needed it. I was a ball of stress. A successful and productive ball of stress, as balls of stress go, but it wasn’t pretty. The vast majority of my products are to meet a personal need. I see the things that I still struggle with and figure I’m not the only one. If I’m having trouble with stress, so are lots of others.

I’ve long been suspicious of the excessive amounts of linoleic in the modern diet and their contribution to oxidative stress, and if I thought a couple hundred milligrams of the stuff were going to be a problem, I wouldn’t have put PS in my daily stress response supplement. The amount of linoleic acid you’ll get from a PS supplement is negligible. So, it’s really nothing to worry about.

But let’s say the linoleic acid is a problem. How does the “threat” of linoleic acid intake stack up against the risk posed by chronic stress? I’m no fan of massive doses of LA. And the data that previously claimed to show cardiovascular benefits from replacing saturated fat with vegetable oils high in linoleic acid is crumbling under new evidence. If there is an inverse association between LA intake and heart disease, it’s probably the nuts, not the isolated seed oils. How about stress?

I’d take the couple hundred milligrams of LA every time.

As for krill oil, it has phosphatidylcholine, a good and worthy nutrient in its own right, but its possible phosphatidylserine content has yet to be quantified or established. Take it as a good omega-3 supplement, by all means, just not as a replacement for PS.

Thanks for using Primal Calm, by the way. I’m glad it’s helping.

Hey Mark,

I was wondering what your thoughts are on sleeping position? I recently started sleeping on my back instead of on my side and I feel more refreshed in the morning. Is there anything to it or is it my imagination?

Also, I’ve started sleeping outside in a tent or on a cot about once a week. There’s just something exhilarating about waking up to the birds singing and other natural noises. Are there any health benefits?



I’m unaware of any solid research into the health effects of sleeping in different positions. Whatever allows you to get the best, most uninterrupted sleep is probably “healthiest.” But I see a few issues with how most people sleep on their sides:

The shoulders: When you place the bulk of your weight on one shoulder, that shoulder tends to sag inward. This pulls your thoracic spine on that side into kyphosis (the rounded upper back we see in laptop warriors and high-frequency texters). And that happens all night long, with your bodyweight pressing down and establishing that shoulder position as the “norm.” Side sleeping can often aggravate or even predispose a person to shoulder injuries, and if you’ve got poor thoracic mobility and a strong tendency toward kyphosis of the shoulder blades, sleeping on either side will exaggerate the kyphosis of that side.

The lower back: When most people sleep on their sides, they form a severe S-shape by curling their lower back. Bending the legs is fine and totally normal, but since a lot of people have lost overall flexibility, bringing the legs up often means bending at the lower back to accommodate the stretch.

Sleeping on your back eliminates those issues, allowing a more neutral spine and symmetrical shoulder placement. In back sleeping, your posture is more “open,” for lack of a better word, and this may allow more “flow” (for even greater lack of a better word) through your tissues. Nobody likes being all hunched over and compressed, yet that’s what many side sleepers are doing for six to eight hours a night, every night.

Sleeping outside is the absolute best. And it’s really, really good for you.

A 2013 study found that going camping for a couple weeks fully restored a person’s circadian rhythm to its natural setting. Their internal biological clocks hewed to the solar cycle. Once darkness fell, biological nighttime ensued — exactly how it works in wild animals.

“Camping,” in this study, was quite strict. The camping trip eliminated all artificial light: flashlights, smartphones, no electric lanterns blaring out pure white light once the sun goes down. Only natural light was allowed: the sun, the stars, the moon, the campfire.

One fascinating finding was that while camping, the melatonin offset occurred 50 minutes prior to wakeup. During artificial light exposure, melatonin offset occurred 2 hours after wakeup. The melatonin offset marks the low point of circadian brain arousal; this meant that camping participants never actually experienced the morning brain sluggishness because they were sleeping when it happened, while participants in the artificial environment had to contend with sluggish brains two hours after getting up. Which scenario sounds like your normal morning? If your melatonin brain offset is occurring before you wake up, that may explain why you’re waking up so refreshed.

Those natural morning noises you mention, like bird song, can also be powerful entrainers of circadian rhythm in many animals. Sounds from a “large animal colony where there were many cats” entrain the circadian rhythms of isolated domestic cats, common house sparrows’ circadian locomotor rhythms are entrained by the playback of pre-recorded bird song, and when the master pacemaker is partially disabled in squirrel monkeys, the role of sound in circadian rhythm entrainment becomes more prominent.

What about people?

A 2004 study found that playing bird song to human subjects late at night in dim light (dim enough not to affect melatonin or circadian rhythm) phase-delayed their circadian rhythms. These delays were “comparable in direction and/or relative size to those produced by other nonphotic stimuli in humans, including exercise,” as well as those “produced by light.” Of course, it’s worth noting that “non-ecological” noises can produce similar phase shifts in other species, so the birdsong may not be completely necessary. Any loud noise might help.

But a Harley revving up in your neighbor’s garage at 6 AM certainly isn’t as pleasant to wake up to as a lilting nightingale’s call. Those people in the study were hearing bird calls in the middle of the night, exactly when you don’t want a circadian phase shift. But hearing bird song in the morning as sunlight streams through your tent might be just the ticket to a healthy, natural (which in this case absolutely means “good”) circadian rhythm in tune with the sun.

That’s it for today, everyone. Let’s hear from you:

Have you tried phosphatidylserine? Notice any benefits? How do you like to sleep? Back, stomach, side? And if anyone out there’s slept outdoors, has it helped?

Thanks for reading.

TAGS:  dear mark

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

If you'd like to add an avatar to all of your comments click here!

45 thoughts on “Dear Mark: The Linoleic Acid Content of Phosphatidylserine, and Optimal Sleeping Position/Location”

Leave a Reply

Your email address will not be published. Required fields are marked *

  1. I guess I’m waking up to the birds whether I like it or not–we sleep with the windows open, and the cats jump to attention at the first chirp of a bird (usually around 3:30 A.M.), and demand to be let out to hunt it. If I don’t snap to attention and let them out, they spend the rest of the night walking all over me, so I can’t get back to sleep. They know that if they pester me long enough, I usually succumb and let them out–then I go back to bed and sleep peacefully for another couple of hours or so.

    1. I used to have that option, too, but then summer hit us in Tampa, and it is way too hot to have the windows open. I will have to wait until fall to do it again. I really liked having the sun and birds wake me me, except for a certain owl I wanted to punch for hooting into my window. Aside from him, it was really enjoyable. My window overlooks a pond new a preserve, so I can get a real symphony of other animals as well.

    2. Outdoor pet cats kill millions of birds and small mammals and lizards every year and also live shorter lives in general. It sounds like you don’t care about the birds and the mammals but it you care about your cats, you should keep them inside.

      1. Could you give us some references for the “millions” of small wild animals killed every year by domestic cats?

        I’m feeding a feral cat and now it hangs around on the back covered patio most days and nights, so I guess I’m helping to preserve the myriad of lizards that are all around, and sometimes in, our house. I saw the cat catch, and eat, a wee mousie once, after I had fed it.

        As to birds, it doesn’t even make the attempt. I’ve watched starlings come down to eat some of the kibble the cat didn’t finish off, and the cat would be six or seven feet away, and would barely open its eyes.

        1. Oddly, the better the cat is fed at home the better the hunter they are outside. There was an article in Scientific America a few years back that spoke about the decimation that outdoor cats do on reptiles and birds, and it’s hard for them help bring back species that are threatened or endangered because of that. That being said, you shouldn’t be outdoor cat shamed for having an outdoor cat. Some cats aren’t good inside, some are feral, etc. etc. So it’s really a case by case basis, but disease is spread easier in the feline community because of outdoor cats and many cat owners don’t get the shot for feline HIV and we see so many cases of that in the shelter I volunteer at and those cats have to be segregatedand can only go to homes with cats that have it. That kind of thing is a huge problem.

        2. Who is “us”? Cat owners? I own a cat, and I keep her indoors for the reason I mentioned above.

          Here is one link throwing doubt on one study’s numbers, but still acknowledging that the number of wild, native species killed is in the tens of millions.

          Here’s another one, from a sportsman’s group called the Wildlife Management Institute. Not exactly a soft and squishy animal welfare group.

        3. Is feeding a feral cat primal? I think not. I put that in the same category as those feeding the nuisance ducks in our neighborhood — please don’t or at least think again. If you like cats, get one and keep it inside.

        4. The feral cat I feed used to live under a house nearby. The people that lived there trapped it and took it to the vet and had it spayed so, at least, it can’t reproduce, then they set it free again.

          I live in a semi-rural area and I see many cats on my daily walk, some are feral, most are not. I have not noticed a drastic decline in the wild, small animal population. In fact, we have ground squirrels all over the place and they have been a bubonic plague vector in the past. I don’t think cats can catch the average ground squirrel but I wish they could.

          As to feeding feral cats not being primal, how do you think dogs and cats became domestic in the first place?

          One last thing, I occasionally see a coyote with a dead cat in its jaws. Nature will balance.

        5. Sounds like you are able to conduct some pretty scientific population studies while you walk around your semi-rural area. Also, since your cat doesn’t seem interested, that must mean no cats ever attack birds.

          Your reasoning and logic are not making a good case for your position that cats really pose no threat.

        6. Sarcasm aside, AlphaFoxTrot, I’m only making an observation of what I see. I have an impromptu bird bath on my back patio and see birds of all kinds come up and drink and, yes, take baths too. I have photos, if you’d care to see them.

          However, since the vast majority of the human population live in cities, then the vast majority of the domestic cats must live in cities, also. Not a lot of good hunting grounds in the cities I would imagine. Although domestic or feral cats in cities catching and killing rats and mice is probably a good thing.

          There are huge swaths of land in the U.S., millions of acres, with no domestic cats and probably darned few feral cats, but there are plenty of birds and lizards and snakes and rodents. I’m not really concerned about lizards, of which we have plenty around here, or birds, of which we have even more than plenty around here, becoming decimated by cats, domestic or feral.

          I would say that agriculture with it’s plowing and herbicides and pesticides cause more deaths of these animals than the domestic/feral cat population. But that’s just a guess because I haven’t done a scientific investigation. So let’s get rid of agriculture to save all the wee mousies, eh. (Okay, I apologize for the sarcasm.)

      2. I have had cats & dogs my entire life( I’m 52)
        & they have always gone outside to play,pee, & poop. That does not mean I do not love my pets and it always bothers me when someone suggests that. There is a quality of life issue as well, I know that I personally would prefer a life of freedom & outdoor play
        even if that life were shorter. OK I will stop my rant, everyone have a nice day.

        1. No one is suggesting you don’t love your animals. I am suggesting that there is significant damage being done to wild, native bird and mammal species and the data supports that. Is that OK as long as the cats get to live “lives of freedom & outdoor play”?

          Is the cost of millions of native species worth it so invasive cats can be happy?

    3. I show bantam chickens. I wake up to bird sounds every single morning, and then I get to eat the breakfast they provide…lots of little eggs.

  2. Sigh. I miss sleeping on my back (currently 26 weeks pregnant.) I have horrible TMJ issues and found they improved significantly once I stopped sleeping on my side.

    1. I’m 28 weeks along, and I am with you! I am a back sleeper and, wow, do I miss that. The body pillow helps, but it’s not the same as sleeping in my preferred position, that’s for sure,

  3. Doesn’t sleeping on your back make you more likely to snore? It is one of the reasons I try to not entirely sleep on my back, plus I really grope my pillows and wrapped myself up in them. As for the shoulder issues, I can definitely see that, as there are many times I have to readjust in order to get a “perfect” position to fall asleep in a comfortable manner.

    1. Yes sleeping on your back can cause your airway to collapse and initiate snoring. Happens to me all the time. For us guys it appears there really isn’t a good sleep position since they all have some negative repercussions. I would like to see more people address this one. My doctor says I can take a decongestant at night and that will reduce the likelihood of my throat closing or allergy pills, etc but what about a drug free alternative? Also no CPAP machines.

      1. We are currently trying the athlete nose strips which increase airflow through the nasal passage – the type you see stuck across a marathoner’s nose! And I think it does help. I’ve also been trialling using micropore tape over my mouth so I can’t mouth breath whilst asleep – this really stops snoring. And apparently mouth breathing initiates stress hormones whereas nose breathing much less so, so in theory at least you should have a more relaxed, restorative sleep state.

        There’s just been an online sleep summit and some of the speakers did address sleeping position, two dentists in particularly who become involved with poor sleepers due to apnoea and jaw issues. Was quite fascinating.

        For the small-jawed, crowded-jaw fraternity back sleeping increases interrupted sleep issues due to breathing issues.

        Ester Gokhale has a great section on sleep position in her book 8 Steps to a Pain-free back. She shows you exactly how to position yourself for side-sleeping, definitely worth following, really helps with the kyphosis.

        Also very important is the pillow used, a speaker from the summit said if you can fold your pillow in half and it doesn’t spring back it’s time to buy a new one! I’ve done just that and it certainly makes posture much better across the shoulders.

        1. Really interesting! It’s the second time I read the advice of taping the mouth shut but I can’t stand the smell of medical tape. I seriously think it smells toxic, I won’t be able to sleep with it under my nose for sure.

    2. I snore when sleeping on my back and I mouth breath and wake up with a mouth so sticky I can barely swallow. That doesn’t happen when I sleep on my side.

    3. Ha Ha ….. I glad to see that I’m not the only one. I don’t have any breathing issues and yet, whenever I sleep on my back, I wake myself up at the 1st sound of me snoring; so I succumb to sleeping on my sides. I never had the issue in my youth and would like to be able to sleep that way, so perhaps I should pick up Yoga again. Plus, I experience weird if not hunted dreams when sleeping on my back. Go figure…. (-;

  4. I’ve stopped sleeping on a mattress and adapted to a Japanese futon on tatami mats. I was a L side sleeper for decades and have had problematic shoulders and lower back issues! The softness of the mattress allowed me to sleep in one position too comfortably, the firmness of the futon/mat combo makes it so I move often throughout the night. It took a few nights to not wake up every time I had to shift. Now I sleep better, move more often, and have an added bonus of getting up and down from the floor more often. Pillows are also an orthotic, but getting out of the pillow habit should be done carefully and slowly (as one would getting into minimal shoes). Not using a pillow means when you are on your side, your neck is getting stretched on one side. This could of course be a problem if you only sleep on one side, but now my neck gets stretched on both sides and I am doing all that for my body when I’m getting my 8-9hrs.

    1. I am very interested in the way you sleep. Please send me a link or a starting point for research. Thanks

  5. I have always been a flat on the back sleeper. I don’t snore either. I think snoring is more a function of excess weight and/or alcohol use than sleeping on the back.

    I have a fairly firm futon mattress and I also use a very flat pillow so as not to crank my neck up unnatural positions either. I think this sort of mimics sleeping on the ground which is how we slept as humans for millennia.

  6. I’m on board with the outdoor sleeping idea and the house we are renting has a screened in porch. I’m getting an eye mask to deal with the light pollution, and going to do this within two weeks! Thanks for the push, Mark!

  7. I sleep with blackout curtains and the most amazing mattress you will ever find, but it just doesn’t compare to sleeping outside. When I’m camping, I wake up feeling more refreshed and energised than I ever do in a normal bed, often with less actual sleeping time too. Whether it’s waking up to the sunrise, sleeping close to the earth, avoiding artificial light all day or a combination of the three – you just can’t beat it.

  8. Whenever we go down to Costa Rica I get the best sleep ever. The twelve hours on and twelve hours off of sunlight everyday is super amazing, and I always wake up with either the Howler Monkeys, the Amazons, or the freaking Toucans. I love it and I sleep through the night there. Sometimes in a hammock. Bliss.

  9. Matthew, honest question, how will you handle stress when you lose your props?

  10. I ve found myself sleeping more on my back lately because shoulder pain wakes me up sleeping on my side. Any suggestions for a good pillow….I ve tried many – currently using buckwheat which was great at first but now my neck is getting wonky. Something preferably natural fiber.

    1. I sleep on my arm. Put your wrist just above your ear and your other wrist between your neck and shoulder.

  11. Interesting and informative stuff as always. My sleep specialist physician advised me to sleep on my side as much as possible claiming sleeping on my back reduces air intake. I was on a CPAP for several years (he said I had the lowest BMI of any of his patients, that it was my nasal construction) and ended up losing 30 pounds and now off it. I’m TOO light weight I think at the present at 5′ 8″ and 138 pounds but due to groin and hernia problems have not been able to exercise and combined with a primal diet lost weight (I’m trying to up my intake of fat). I do notice my shoulders hurt after a while, I tend to move from one side to the next. When I lay on my back I don’t use a pillow so my neck is not thrust forward. I end up a lot in a “hybrid back / side” position which is probably not good either lol.

  12. I started to sleep without a pillow about a year ago. It was a hard transition to make because I like to fall asleep on my side. I now sleep with a very thin pillow as I couldn’t hack not having something under my head.

    I was interested in sleeping without a pillow as this is how babies and young kids sleep. Our pillows are often so stuffed that they push our heads forward when sleeping on our backs. Since I try to live a primal life, I figured I’d give this a shot. I hope to get back to sleeping without a pillow again. My neck and upper shoulders felt great.

    1. Hello Anita,

      I also tried it but I don’t think it’s sustainable for most of us. I watched a baby’s sleep patterns for months and YES, it starts on the back and then it rolls one side or on tummy and YES it doesn’t use a pillow.

      But while sleeping on the back does work without a pillow go either side and it will hurt your neck, especially when using tough surfaces. It’s mainly because on an adult there’s a bigger gap as compared to any baby.

      You can start here and see why for thin adults or those sleeping on spongy mattresses side sleeping without pillow might work.

      How do I sleep? I have a small pillow on a tough / straight wood board with two blankets over it.

  13. Regarding the PS. Ive been reading online about the sources, and apparently you can get a lot from beef brain and also chicken hearts.

    A good a reason as any to try out some offal!

  14. I can only sleep on my tummy. If I want to stay away all night I lay on my back. Sleep does not come…. yeah, long flights are hell….

  15. I sleep on my stomach or my right side, rarely on my left side. If I try to sleep on my back I wake up and have to change positions. I am also normally a mouth breather, always have been
    due to hayfever type allergies. This spring my allergy symptoms were almost nonexistent. I am crediting Black Cumin Seed Oil but I have no way to know for sure. Maybe I finally outgrew them like the doctor said I would( at 52 lol ).

  16. I am a dentist specialising in physiologic sleep appliances. Any person who wakes not feeling refreshed or with headaches and/or jaw pain, should do an overnight sleep study to rule out sleep apnoea or upper airway resistance. If you snore you definitely have a degree of sleep disordered breathing ( weight increases the risk but even slim people can differ due to the anatomy of the jaws , nasal airway and the airway itself). However you can not snore but still have sleep apnoea. CPAP is the gold standard for treatment however many patients who have mild or moderate sleep apnoea or upper airway resistance ( very common in fit slim females ) can be treated successfully with a mandibular advancement appliance, made to your physiological rest position. These are easy to wear, easy to take with you eg camping/ travel. No drugs no surgery. Having obstructive sleep apnoea increases your risk of cardiovascular disease by three times not to mention increase risk of stroke, diabetes, possibly Alzeimers to name a few. Considering all the efforts we make to fine tune our health it makes no sense to ignore this. As mentioned nasal breathing is essential so an ENT assessment may be needed to ensure nasal breathing. Mouth taping is very effective.
    Back sleeping increases the risk of the jaw falling back and blocking the airway so in most cases side sleeping is preferable. I’d rather risk a sore shoulder than dying in my sleep.
    So do some research into the appliances. But like most things medical you need to find a dentist who follows a physiologic approach.

  17. Thank you Mark for your patient response to my question – upon further research and thought after I sent it, I also came to the same conclusion.

    My question may seem silly (half a gram of linoleic acid, so bad!!!), but my concerns hinged on the higher bio-availability of fatty acids delivered in phospholipid form. The main reason krill oil is supposedly more effective than fish oil at a third of the dose is the phospholipids, so, what would the effect of taking linoleic acid in phospholipid form be, given that an average krill oil dose of 1000mg equals about 200mg of EPA/DHA?

    The original clinical studies into PS were done using bovine-derived product, and thus some question the efficacy of the newer plant-derived products – the argument seems to be that the animal omegas were a key part of the reason for the efficacy of the product (which makes sense). However, is this due to the fact that animal-derived PS is uniquely effective vs the plant-derived PS (some sort of unique magic in the molecular structure perhaps?), or is simply that the people in the studies were not getting any other effective animal omega-3 source? After consideration, I’m inclined to think it’s the latter, and decided that phospholipids or no, half a gram of extra linoleic acid a day via this source is probably neither here nor there, especially seeing as I’m taking it with krill oil as well.

  18. I like to sleep in a number of different and creative positions, then when I go to sleep I usually lye on my side.

  19. Some people are more likely to suffer sleep paralysis attacks/nightmares when sleeping on their backs. Hence the old warning in some traditions about the devil getting you if you sleep on your back.

  20. How does one submit a question to “Dear Mark?” Am I overlooking a link?