Berkeley scientists discover the secret to waking up alert and refreshed

Wake up well

Researchers at the University of California, Berkeley have found that by focusing on three key elements – sleep, exercise and breakfast – one can wake up refreshed and alert each morning.

Tips the researchers found: Sleep longer and later, exercise the day before and have a low-sugar, high-carbohydrate breakfast.

Do you feel sleepy until you’ve had your morning coffee? Do you suffer from drowsiness during the working day?

If you struggle with morning wakefulness, you’re not alone. However, a new study from the University of California, Berkeley, shows that waking up refreshed isn’t just a matter of luck. The scientists found that paying attention to three factors – sleep, exercise and breakfast – can help you start your day without feeling drowsy.

The findings come from a detailed analysis of the behavior of 833 people who were fed a variety of breakfast meals over a two-week period; wore wristwatches to record their physical activity and sleep amount, quality, timing and regularity; diaries kept of their food intake; and recorded their alertness level from the moment they woke up and throughout the day. Twins – identical and fraternal – were included in the study to untangle the influence of genes on environment and behavior.

What affects an individual's alertness on a day-to-day basis

In the new study, Vallat, Walker and their colleagues looked at the influence of genes and non-genetic factors, including environment, on awakening alertness. By measuring how alertness varies between individuals and in the same person on different days, they were able to unravel the role of exercise, sleep, type of breakfast and a person’s post-meal glucose response. Credits: Raphael Vallat and Matthew Walker, UC Berkeley

The researchers discovered that the secret to alertness is a three-part recipe: exercise a lot the previous day, sleep longer and later in the morning, and a breakfast high in complex carbohydrates and low in sugar. The researchers also found that a healthy controlled blood glucose response after breakfast is key to waking up more effectively.

“All of these have a unique and independent effect,” said UC Berkeley postdoctoral fellow Raphael Vallat, the study’s first author. “If you sleep longer or later, you will see an increase in your alertness. If you increase your exercise the day before, you will see an increase. You see improvements in each of these factors.”

Morning drowsiness is more than just an annoyance. It has major social consequences: many car accidents, industrial accidents and large-scale disasters are caused by people who cannot shake off drowsiness. The Exxon Valdez oil spill in Alaska, the Three Mile Island meltdown in Pennsylvania, and an even worse nuclear accident in Chernobyl, Ukraine, are well-known examples.

“Many of us think of morning sleepiness as a benign annoyance. However, it costs developed countries billions of dollars each year through lost productivity, increased health care utilization and absenteeism. Matthew Walker, professor of neuroscience and psychology at UC Berkeley.”From car accidents to work-related accidents, the cost of sleepiness is deadly. As scientists, we need to understand how we can help society wake up better and how we can help reduce the deadly cost for society’s current struggle to effectively wake up each day.”

Vallat, Walker and their colleagues recently published their findings in the journal

A personalized approach to eating

Walker and Vallat teamed up with researchers in the United Kingdom, the U.S, and Sweden to analyze data acquired by a U.K. company, Zoe Ltd., that has followed hundreds of people for two-week periods in order to learn how to predict individualized metabolic responses to foods based on a person’s biological characteristics, lifestyle factors, and the foods’ nutritional composition.

The participants were given preprepared meals, with different amounts of nutrients incorporated into muffins, for the entire two weeks to see how they responded to different diets upon waking. A standardized breakfast, with moderate amounts of fat and carbohydrates, as compared to a high protein (muffins plus a milkshake), high carbohydrate, or high sugar (glucose drink) breakfast. The subjects also wore continuous glucose monitors to measure blood glucose levels throughout the day.

The worst type of breakfast, on average, contained high amounts of simple sugar; it was associated with an inability to wake up effectively and maintain alertness. When given this sugar-infused breakfast, participants struggled with sleepiness.

In contrast, the high carbohydrate breakfast — which contained large amounts of carbohydrates, as opposed to simple sugar, and only a modest amount of protein — was linked to individuals revving up their alertness quickly in the morning and sustaining that alert state.

“A breakfast rich in carbohydrates can increase alertness, so long as your body is healthy and capable of efficiently disposing of the glucose from that meal, preventing a sustained spike in blood sugar that otherwise blunts your brain’s alertness,” Vallat said

“We have known for some time that a diet high in sugar is harmful to sleep, not to mention being toxic for the cells in your brain and body,” Walker added. “However, what we have discovered is that, beyond these harmful effects on sleep, consuming high amounts of sugar in your breakfast, and having a spike in blood sugar following any type of breakfast meal, markedly blunts your brain’s ability to return to waking consciousness following sleep.”

It wasn’t all about food, however. Sleep mattered significantly. In particular, Vallat and Walker discovered that sleeping longer than you usually do, and/or sleeping later than usual, resulted in individuals ramping up their alertness very quickly after awakening from sleep. According to Walker, between seven and nine hours of sleep is ideal for ridding the body of “sleep inertia,” the inability to transition effectively to a state of functional cognitive alertness upon awakening. Most people need this amount of sleep to remove a chemical called adenosine that accumulates in the body throughout the day and brings on sleepiness in the evening, something known as sleep pressure.

“Considering that the majority of individuals in society are not getting enough sleep during the week, sleeping longer on a given day can help clear some of the adenosine sleepiness debt they are carrying,” Walker speculated.

“In addition, sleeping later can help with alertness for a second reason,” he said. “When you wake up later, you are rising at a higher point on the upswing of your 24-hour circadian rhythm, which ramps up throughout the morning and boosts alertness.”

It’s unclear, however, what physical activity does to improve alertness the following day.

“It is well known that physical activity, in general, improves your alertness and also your mood level, and we did find a high correlation in this study between participants’ mood and their alertness levels,” Vallat said. “Participants that, on average, are happier also feel more alert.”

But Vallat also noted that exercise is generally associated with better sleep and a happier mood.

“It may be that exercise-induced better sleep is part of the reason exercise the day before, by helping sleep that night, leads to superior alertness throughout the next day,” Vallat said.

Walker noted that the restoration of consciousness from non-consciousness — from sleep to wake — is unlikely to be a simple biological process.

“If you pause to think, it is a non-trivial accomplishment to go from being nonconscious, recumbent, and immobile to being a thoughtful, conscious, attentive, and productive human being, active, awake, and mobile. It’s unlikely that such a radical, fundamental change is simply going to be explained by tweaking one single thing,” he said. “However, we have discovered that there are still some basic, modifiable yet powerful ingredients to the awakening equation that people can focus on — a relatively simple prescription for how best to wake up each day.”

It’s not in your genes

Comparisons of data between pairs of identical and non-identical twins showed that genetics plays only a minor and insignificant role in next-day alertness, explaining only about 25% of the differences across individuals.

“We know there are people who always seem to be bright-eyed and bushy-tailed when they first wake up,” Walker said. “But if you’re not like that, you tend to think, ‘Well, I guess it’s just my genetic fate that I’m slow to wake up. There’s really nothing I can do about it, short of using the stimulant chemical caffeine, which can harm sleep.

“But our new findings offer a different and more optimistic message. How you wake up each day is very much under your own control, based on how you structure your life and your sleep. You don’t need to feel resigned to any fate, throwing your hands up in disappointment because, ‘… it’s my genes, and I can’t change my genes.’ There are some very basic and achievable things you can start doing today, and tonight, to change how you awake each morning, feeling alert and free of that grogginess.”

Walker, Vallat, and their colleagues continue their collaboration with the Zoe team, examining novel scientific questions about how sleep, diet, and physical exercise change people’s brain and body health, steering them away from disease and sickness.

Reference: “How people wake up is associated with previous night’s sleep together with physical activity and food intake” by Raphael Vallat, Sarah E. Berry, Neli Tsereteli, Joan Capdevila, Haya Al Khatib, Ana M. Valdes, Linda M. Delahanty, David A. Drew, Andrew T. Chan, Jonathan Wolf, Paul W. Franks, Tim D. Spector and Matthew P. Walker, 19 November 2022, Nature Communications.
DOI: 10.1038/s41467-022-34503-2

The study was funded by Zoe Ltd.

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