Why do we crave sugar when we’re sleep deprived (and what can we do about it)?
TL;DR: Sleep deprivation causes results in too much cortisol being in our blood during the day. This helps us stay awake but it also interferes with insulin signaling, causes sugar cravings, and increases fat storage. (about 7 min read)
Metabolic tips to help you “reset” and reduce sugar cravings:
Even though you’re tired, do something active in the morning. This can be as simple as doing 20 jumping jacks, brushing your teeth, then doing 20 more. Getting your blood moving will help get your metabolism back in balance.
Stay hydrated throughout the day to help your kidneys filter out hormones/chemical signals that your body doesn’t need any more. “Cleaning up” your blood reduces stress.
Be aware that your sleepiness is tricking you into feeling hungry for sugar. Keep some high-fiber and/or high-protein snacks on hand to feel full. These foods won’t raise your BGLs quickly, so you will release less insulin and store less glucose as fat.
Your body “cleans house” while you’re sleeping. This includes cleaning up all the chemical and hormone signals it released during the day so you could properly respond to your environment. The house-cleaning is done by specific cells in your immune system called macrophages (macro = big; phage = eater). Macrophages make things better by literally eating their way out of a problem. (Same.) Ideally, your macrophages would go through and clean up while you’re sleeping so you can get a fresh start for the next day, which will have it’s own challenges you need to respond to.
Leftovers in your fridge are good to eat later; leftovers in your body’s hormone/chemical signaling cause you to eat when it’s not good. If macrophages can’t do their job and clean things up, the debris from yesterday gets mixed in with the signals from today and it’s a clutter-fu… mess. It’s a mixed-up mess of yesterday's and today’s signals and your body has a hard time knowing how to respond since it isn’t clear what signals it should be listening to. Messy signals = stress in your body. And stress = metabolic imbalance.
Sleep deprivation increases cortisol levels which interfere with insulin signaling. Cortisol should naturally increase overnight and be at a peak in the morning; this is what wakes you up. It’s normal to have elevated cortisol levels in the morning. In fact, doing things that increase cortisol in the morning - like drinking coffee or exercising - helps us wake up. But when we’re sleep-deprived, cortisol levels stay high all day.
Why is this a problem? If cortisol helps us “wake up” and we feel sleepy, then wouldn’t we want higher cortisol levels on days when we didn’t get enough sleep and need a boost? Well, yes, we could benefit from the increased “wakefulness” that the extra cortisol gives us. But there’s a trade-off: cortisol also interferes with insulin signaling.
Cortisol and insulin are frenemies. We discussed this in the post about how eating simple carbs along with coffee can lead to a bigger “sugar crash” if you don’t move around afterward than you would get if you ate simple carbs without the java or drank coffee without the croissant. Cortisol is a signal that your muscles should start moving, so it tells all your other cells to wait a little bit before taking glucose out of the bloodstream. This gives your muscles a chance to use that glucose for energy first, which also brings down your blood glucose levels (BGLs). However, if you don’t move around after eating, then your muscles don’t help bring down your BGLs and the job of keeping your BGLs from staying high falls all on insulin.
Since cortisol interferes with insulin signaling, your pancreas ends up putting more insulin is put into the bloodstream than it should. Too much insulin leads to too much glucose being pulled out of the blood and BGLs drop below where they should be (aka hypoglycemia). This makes us feel tired and crave sugar.
Insulin is a growth factor. If your body is relying on insulin only - and not the movement of your muscles - to get your BGLs from being too high, you will be storing the simple carbs you eat as glycogen (starch in animal cells) or fat. There is a limit to how much glycogen your body will store. You make room for more glycogen to be stored when you use the glycogen you already have. Glycogen gets used up when you fast, when you move your muscles, or when you eat a low carbohydrate/ketogenic diet.
If you aren’t moving that much, or if you aren’t fasting, and you eat simple carbohydrates, you will store the excess glucose as fat.
Press “reset” by staying hydrated and getting your blood moving. Is there a way we can help “clean up” yesterday’s leftover signals that were left lying around when we didn’t get enough sleep? Staying hydrated, getting our blood moving, and being aware that the sugar cravings are a “typo” in our body’s messages can help subvert the sugar cravings and keep us on track with our fitness and health goals.
If the message is truly a leftover message, your body won’t be producing more of it, so doing things that help your blood filter through your liver and kidneys faster will help your body reset and rebalance. Staying hydrated essentially just drowns the old signals out and helps your kidneys filter them out of your body faster. Exercise will get your blood circulating faster. Being aware that this is happening won’t filter your blood faster but it can help you make informed choices about which snacks you want the day after you didn’t sleep well.
Metabolic tips to help you reset and reduce sugar cravings:
Even though you’re tired, do something active in the morning. This can be as simple as doing 20 jumping jacks, brushing your teeth, then doing 20 more. Getting your blood moving will help get your metabolism back in balance.
Stay hydrated throughout the day to help your kidneys filter out hormones/chemical signals that your body doesn’t need any more. “Cleaning up” your blood reduces stress.
Be aware that your sleepiness is tricking you into feeling hungry for sugar. Keep some high-fiber and/or high-protein snacks on hand to feel full. These foods won’t raise your BGLs quickly, so you will release less insulin and store less glucose as fat.
