Dear Mark: Dealing with Undersleeping, and the Nutritional Value of Yeast

YawnFor today’s edition of Dear Mark, we’ve got two questions. First up is a big one: how do you deal with the inevitable bout of acute sleep loss? Are there pills to take, exercises to do or avoid, foods to eat or not? Or are we completely helpless in the face of undersleeping? And second, I discuss the importance – or not – of yeast in the diet. Are we missing out on an integral part of the human diet by avoiding the yeast found in bread?

Let’s find out:

Hi Mark

We all agree that getting enough sleep is important on all levels, and a good sleeping routine is vital to ensuring a good night’s sleep. However, what can we do when sleep deprivation cannot be helped – e.g. new mothers, sudden stress induced insomnia, deadlines, travel etc. – to help ourselves the day following such sleeplessness to counteract the bad effects/generally help us get through the day (without getting into a sleepless cycle, i.e. too much coffee)? Should we attempt to sleep in? Should we take more supplements that day? Eat more primal carbs? Take naps? Take the day off from exercise? Or exercise to induce fatigue? No strength training but cardio is ok? Go to bed earlier? Would really appreciate your thoughts on how to deal with “undersleeping”. Thank you!


Great question. Sleep deprivation is sometimes unavoidable, but we don’t want it to totally undermine our efforts to be healthy. By identifying the specific and known health effects of sleep deprivation, we can propose physiologically plausible solutions or temporary workarounds. A 2010 review of the endocrine effects of sleep deprivation on humans provides a good overview:

Glucose tolerance goes down. This is a well-known phenomenon, and it’s probably one reason why chronic sleep loss is a big risk factor for diabetes.

Solution: Avoid unnecessary carbohydrates. The more intolerant you are to carbs, the more body fat you’ll gain when you eat them. The day after bad sleep should be lower carb than a day after good sleep.

Appetite increases. Leptin, the hormone that signals satiety, is lowest in people with sleep debt. In a cruel twist of fate, people who haven’t slept tend to crave carbohydrates and junk food more than any other food. Their ability to resist these cravings also decreases.

Solution: “Don’t eat so much” doesn’t really work for most people, especially if your body is telling you to eat as much as possible. Some of us can simply go without and be fine, but others have this weird inability to easily ignore the body’s physiological impulses. If you feel like snacking, try pistachios. The little green nuts improved glucose metabolism and insulin resistance in a recent randomized controlled trial. Anything with cinnamon is also good, since the spice improves insulin sensitivity following a bad night’s sleep.

Cortisol rhythm grows discordant. Normally, cortisol is highest in the morning (to wake you up) and drops through the day until the evening, when it’s lowest (to let you get to sleep). Under sleep debt, cortisol is still high in the morning, but the drop-off throughout the day is far more gradual – and at night, cortisol remains elevated enough to disrupt the quality sleep you so desperately need.

Solution: There are several things you can do throughout the day to help normalize your cortisol levels.

  • Meditate, especially at night before bed. Meditation has a remarkable stultifying effect on cortisol.
  • Eat your carbs at night. Carbohydrate can lower cortisol in the short term but sleep loss has made you glucose intolerant, so limit your carbs to night.
  • Go easy on the exercise. Walk, don’t run; walking lowers cortisol. Even better, go walk through a forest, a park, the beach, or anywhere out in nature for even more cortisol reduction. If you lift, keep the volume low. Go for singles and doubles instead of sets of 12. If you promised your buddy you’d run hill sprints with him, make them super short – like 3 or 4 seconds long.
  • Don’t not eat. Fasting will probably just exacerbate the sleep deprivation stress you’re experiencing. Stick to protein, fat, and limit (but don’t eliminate) the carbs.

Your blood pressure goes up. When you haven’t slept, your body is on high alert. The sympathetic nervous system kicks in, your pulse pounds, you’re all sweaty and disoriented in this alternate reality you’ve stumbled into, and your blood pressure spikes. That explains the “tired but wired” zombie-esque head space we’ve all felt after a bad night of sleep.

Solution: Get some bright light and sun, but not too much strong sun (a disrupted circadian rhythm also increases your skin’s susceptibility to UV damage). However, sun exposure does release nitric oxide, which lowers blood pressure. It’s also calming, soothing, and just plain enjoyable.

Balance decreases. A night of sleep deprivation disrupts your postural control. In one study, sleep deprived adults had a harder time maintaining their balance; excessive swaying was evident.

Solution: Avoid workouts involving complex exercises requiring coordination between multiple body parts. Stick to simpler exercises, like walking, cycling, pushups, or pullups. Bodyweight stuff. Don’t go for a PR in the snatch today, yeah? You probably won’t hit it and you might hurt yourself.

Intestinal permeability increases. Your gut becomes more leaky after a bad night’s sleep, allowing passage of unwanted and/or harmful irritants, allergens, bacteria, and endotoxins from your gut to your bloodstream.

Solution: Limit foods to which you suspect you’re intolerant. Suspect you have an issue with gluten? Don’t test your luck with a pizza cheat day if you haven’t slept much.

Oh, I almost forgot:

Take a nap. Naps after a bad night’s sleep are exquisite. They’re perhaps my favorite pastime (that I don’t get to do as often as I’d like). It’s going to bed and dropping into the abyss of deep inevitable sleep, except you get to do it twice. Once during the day, once at night. Oh, and naps (even a ten minute nap) are pretty good at helping you recover alertness after sleep deprivation (PDF). They take the edge off.

I’d like to make an important point: if we’re talking a bad night’s sleep every once in awhile, the above recommendations will help and might even mitigate most of the short term issues. But acute sleep loss, while bad, isn’t the real problem. It’s eating a high carb, high junk food diet while getting five hours a night for months on end. It’s going to bed at midnight and waking up for the 5 AM CrossFit class every other day. It’s staying up until 2 AM watching bad TV and eating your weight in gluten. It’s chronic sleep loss/deprivation that’s truly dangerous. These strategies may keep the negative health effects initially, but not for long. Don’t take today’s post as a free pass to skip sleep. It will catch up to you.

Hi Mark,

We already established that mushrooms are beneficial to our health. I was wondering what really is the purpose of yeast – the yeast people make bread with – which is a fungi in the same kingdom as mushrooms.

Are we missing out on yeast in the Primal [Blueprint] diet because we don’t eat bread?

Can you advise if you consider it primal and how can we get it or try to get it in our diet?

Thank You and Kind Regards


Good question. I’ve got good news. Yeast is everywhere. If you’re eating real produce, it’ll have live, active yeast – as long as it hasn’t been subjected to major industrial washing. The blackberries you got at the farmer’s market? Teeming with yeast.

Natural yeast allows fermentation. It’s the natural yeasts and bacteria on cabbage that allow sauerkraut and kimchi. The wild yeasts on grapes allow wine (although most modern vintners add certain dependable species back in after washing the grapes). Both beer brewers, winemakers, and bread bakers use yeasts from the same species: Saccharomyces cerevisiae. Brewer’s yeast is a popular nutritional supplement, too. A couple tablespoons contains:

  • 1.2 mg thiamine (80% of daily value)
  • 1.5 mg riboflavin (90%)
  • 10 mg niacin (50%)
  • 0.8 mg vitamin B6 (40%)
  • 80 mcg folate (15%)
  • 1 mg copper (50%)
  • 63 mcg selenium (90%)
  • 633 mg potassium (18%)
  • 16 grams protein

That’s not bad. It’s also a good source of chromium, a trace mineral that may help insulin resistant people improve glucose tolerance. If you’re really interested in getting baker’s yeast, you can get pretty close by eating brewer’s yeast.

It’s not totally benign, of course. Many people find that they simply cannot tolerate concentrated dietary sources of yeasts (like bread, alcohol, or straight tablespoons of supplemental yeast). A recent study found that hidradentis suppurativa patients are more likely to be sensitive to brewer’s/baker’s yeast and experience fewer symptoms when yeasts are eliminated from the diet.

Bottom line: There are nutritional benefits to baker’s/brewer’s yeast, especially in people who avoid animal products, but a piece of bread isn’t giving you enough yeast to make a difference. To make bread, bakers typically add just a teaspoon of yeast to over a pound of flour. Good luck getting enough yeast to make a dent in your nutrient requirements from bread alone.

You’re not missing much. And if you were, you could just drink a glass of wine with yeast bits floating around or take brewer’s yeast. No need for bread.

Thanks for writing in and reading, everyone!

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.

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