How High-Intensity Exercise Supports Glucose Control After Sleep Loss

Lewis Howes: I saw a WebMD survey that found the average American sleeps 5.7 hours a night. I'm not sure how accurate that is, but 5.7 hours a night. I also saw that the National Institutes of Health says six or seven hours of sleep is not enough and can lead to chronic sleep deprivation. How many hours of sleep a night do humans need to function at a high level? If we don't sleep that much, what does chronic sleep deprivation actually do to the body?

Dr. Rhonda Patrick: The first question is how much sleep people need. There is a general answer, but there are also chronotypes. Genes can affect how much sleep a person needs. Most people need seven to nine hours of sleep a night. However, some outliers have genes that allow them to function well with less than seven hours. That's the exception, not the rule.

Lewis Howes: They can function with less, but does less sleep optimize their body and mind?

Dr. Rhonda Patrick: It's interesting because it has to do with their circadian rhythm, the 24-hour clock that governs our cells, metabolism, neurotransmitter production, and hormone production. When the circadian rhythm is disrupted, things go haywire. Their circadian rhythm is fundamentally a little different, and they can be healthy with less sleep. I don't know much about that exception, so I don't want to focus on it.

Lewis Howes: Is that approximately 1% of the population?

Dr. Rhonda Patrick: I don't know what percentage it is. It's not a lot, but it does exist, and I want to acknowledge that. People will hear "seven to nine hours," and the 1% to 3% who don't need that will yell and scream.

Lewis Howes: They say, "I can function on five hours, and I'm good." Maybe you can function now, but can you function in 20 or 30 years? Will being sleep-deprived now affect your body later?

Dr. Rhonda Patrick: Sleep is a time of rejuvenation and repair. Our repair processes occur when we're sleeping, including the repair of DNA damage to prevent cancer-causing, or oncogenic, mutations. We also repair our brains by clearing protein fragments and aggregates that build up throughout the day. When we sleep, we clean that material out.

A process called the glymphatic system is activated and moves fluid through the brain like a wash. It physically forces material out through the lymphatic system. This is important for preventing the buildup of protein aggregates such as amyloid beta, which is involved in Alzheimer's disease. That's why sleep is so closely connected to neurodegenerative disease. It is a time for repair.

Many things happen in the brain, but sleep also affects metabolism and blood pressure. Blood pressure resets. Everything resets during sleep. Digestion shuts down so that you can do this repair work. Think of your body as a phone. If you don't recharge your phone at night, it dies.

Lewis Howes: It dies.

Dr. Rhonda Patrick: It won't run properly. You have to recharge your battery while sleeping. That includes brain function, immune-cell function, and metabolism. The immune system is also replenished.

I don't think many people consider the metabolic effects. Most people who think about sleep deprivation think about brain fog and not functioning at their sharpest. I don't know that most people think about type 2 diabetes or metabolic syndrome. I certainly didn't until I became a new mother and wore a continuous glucose monitor, a device attached to the arm or abdomen that continually measures blood-glucose levels.

Lewis Howes: When you become a new parent, you're sleep-deprived.

Dr. Rhonda Patrick: Yes, especially as a mother waking up to nurse a child three times a night. Your sleep is very fragmented. I wore a continuous glucose monitor, and what happened to my blood-glucose regulation was eye-opening. It was completely disrupted. My levels looked prediabetic even though I still ate healthy foods such as vegetables, salmon, and blueberries.

Lewis Howes: Blueberries.

Dr. Rhonda Patrick: Blueberries. I wasn't as physically active as usual, especially in the first month after having a baby, but I was going for walks. I wasn't doing my usual run. I eventually started doing high-intensity interval training, which I'll return to as good news. But it was striking to see my fasting blood-glucose levels become so high without really changing my diet.

Even getting one to three hours less sleep per night for three consecutive nights can have an effect. Think about how common it is to get one hour less sleep for three nights in a row.

Lewis Howes: So common. It happens to me all the time.

Dr. Rhonda Patrick: Studies have examined what happens to healthy people without a diagnosed metabolic disease after three nights of getting one to three hours less sleep. Their bodies do not dispose of glucose properly, so blood-glucose levels stay elevated. On top of that, they do not make enough insulin to lower blood glucose. You get a double effect that looks like insulin resistance.

Lewis Howes: Or prediabetes if you look only at the numbers.

Dr. Rhonda Patrick: Yes. Again, this comes from not getting enough sleep for three consecutive nights. It's not full sleep restriction that takes away four or five hours. It's only one to three hours less. Sleep restriction has profound metabolic effects that accumulate. This cumulative effect is called sleep debt. You build up sleep debt as you get less sleep each night.

Lewis Howes: Can you ever pay off the sleep debt?

Dr. Rhonda Patrick: The good news, at least for the metabolic and cognitive effects, is that exercise can help offset much of it. That's also what I learned from my personal experience.

Lewis Howes: I saw a quote from you online: "Even one hour less sleep per night for three nights can disrupt how your body processes sugar and lead to mild insulin resistance." But there is some good news: HIIT can almost reverse it. Can you sleep less, then train hard and reverse the negative effects?

Dr. Rhonda Patrick: According to research, yes, and according to my anecdotal data, yes. There are reasons why. In high-intensity interval training, you perform hard intervals above the effort of a normal jog, reaching approximately 80% to 85% of your maximum heart rate. You work hard for an interval and then have a lighter recovery period. During that vigorous interval, you cannot talk because you're working too hard.

When you work that hard, you push your energy system to use glucose and make a metabolite called lactate. People once thought lactate was a useless waste product, but that was very wrong. Lactate is used by other tissues. Your muscles make lactate because they use glucose when your body cannot deliver oxygen to the muscle fast enough to produce all its energy through the mitochondria. Lactate is then shuttled into the brain, heart, and liver. It is an energetically favorable fuel and a signaling molecule. It's one way muscle communicates with other parts of the body and with itself.

Lactate signals cells to make more or less of something. In muscle, it helps signal for more glucose transporters. These transporters sit below the muscle-cell surface and do not let glucose in all the time. When activated, more transporters move to the surface and allow more glucose to enter.

Lewis Howes: Where does that glucose come from?

Dr. Rhonda Patrick: The glucose comes from food or gluconeogenesis, the process of making glucose from other materials such as glycerol or amino acids.

Lewis Howes: Is it pulling glucose from visceral fat or mainly from food you've eaten?

Dr. Rhonda Patrick: Usually it's from food or glucose stored as glycogen. The important point is that those glucose transporters stay at the muscle-cell surface for approximately 48 hours. Glucose eaten during the next two days can be taken up by muscle very effectively. The net effect of high-intensity interval training is to remove glucose from the bloodstream and bring it into muscle, where you want it.

Returning to sleep, multiple studies show that high-intensity interval training performed before or after sleep deprivation can help. If you perform it within an approximately 48-hour window around getting less sleep, glucose regulation improves because the stress on the muscle increases those transporters. Glucose is taken up more effectively, and exercise also affects insulin signaling through other mechanisms.