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The Relationship Between Metabolism and Sleep

Written by Andrew

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Woman opening fridge

Our sleep and our metabolism are intimately intertwined. Like all major processes of physical homeostasis, sleep plays an important role in the body’s ability to carry out its most vital metabolic functions.

If you’ve ever eaten a very heavy meal and tried to sleep directly after, you are likely anecdotally aware that this is true. The same goes for anyone who has suffered from sleep disorders and noticed a change in their weight and well-being. More and more, sleep and diet researchers are finding links between the quality of our sleep and the ability of the body to process food and nutrients efficiently.

But exactly how are the two processes linked? And what happens to our bodies when we start to lose sleep regularly? Is there a way to boost our metabolic systems by sleeping differently?

Read on for the answers to these questions and to learn more about the connections between sleep and metabolism.

What exactly is metabolism?

Metabolism can be defined as the biochemical processes that must occur to keep an organism alive. For the purposes of this article, we can limit the use of the term to the way the body breaks down calories to provide the body the energy it needs to function. This encapsulates the way we ingest, then digest food and drink.

Obviously, turning the things we eat and drink into usable fuel and building material for the body is a complex process with millions of moving parts. It requires cooperation from the brain, many parts of the body, and the environment a person finds themselves in. All of these factors determine how efficiently our metabolism processes the things we eat.

As we’ll find out, our own behavior when it comes to consumption and sleep also plays a big role.

Metabolism as we sleep

During the course of a normal night of sleep, our body is working subconsciously to maintain itself and our health. Changes in the way we metabolize the things we have ingested is an essential part of this process.

As we move through the sleep cycle, there are significant changes in energy consumption a healthy person should expect to experience in the course of the night. Typically, our metabolism slows about 15% during the night—though it is important to note that it will be higher or lower depending on the exact stage of the sleep cycle we happen to be on at any given time. Growth hormones and cortisol, two majorly important catalysts for proper metabolic functioning, appear to fluctuate systematically during the course of the night in order to maintain the ideal amount of energy consumption and storage that our bodies need.

Sleep disorders and metabolism

One illustrative way to continue examining the relationships between metabolism and sleep is to look at what happens to people’s metabolic processes when they suffer from sleep disorders.

A 2009 paper published in the academic journal Nature Reviews Endocrinology discusses over four decades of research into the subject of sleep disorders and metabolism. The authors write that there is overwhelming evidence that poor or short sleep, especially caused by disruptions associated with sleep disorders, leads to a “deleterious effect on glucose metabolism.”

Metabolizing glucose is essentially the way our body creates energy out of the food we eat. When that process is messed with, we see all sorts of nasty effects, from lethargy and depression all the way to diabetes and obesity.

The paper’s authors also claim that loss of sleep quality and quantity can also lead to problems with the proper functioning of the endocrine system, our bodies’ hormone creating and regulating mechanism. In particular, obstructive sleep apnea (OSA) was singled out as a sleep disorder that was deeply linked to endocrine disorders, as well as obesity and certain kinds of diabetes. As discussed before, hormones play a massive role in regulating the metabolic processes of the body, and any disruption to their functioning can and will lead to big problems with our overall health.

OSA is not alone in causing problems. Any sleep disorder that leads to a chronic drop off in either sleep quality or quantity is likely to affect our bodies’ metabolic efficiencies if it lasts long enough. This includes insomnia, restless legs syndrome (which has been linked in particular to problems metabolizing iron), and more.

Woman weighing herself on a scale

Societal changes in sleep and metabolism

Considering the complex interconnectedness between our sleep health and our metabolic health, it is no wonder that scientists are taking a long hard look at co-existing trends towards worse sleep and increases in metabolic disorders across entire populations.

Authors of the 2009 paper in Nature Reviews Endocrinology claim that as sleep quality and quantity have decreased in the United States (for many reasons, as reported elsewhere) rates of diabetes and obesity have increased. The same goes for endocrine irregularities which seem to be exacerbated by sleep troubles, the authors claim.

As diabetes and obesity continue to be massive, consistently growing problems in the United States, the notion that changes in our national sleeping patterns could be partially to blame represent yet another potential avenue for solutions, along with changes to diet and exercise, that are worth exploring. Scientists recommend that doctors working with patients who suffer from these conditions ought to take time to discuss improving the sleeping patterns of their patients in order to combat these potentially deadly diseases.

Achieving a healthy metabolism with healthy sleep patterns

So what can you do to make sure your body’s metabolic processes are working in the way that they should be?

The short answer is one we often talk about: improve your sleep hygiene and routines.

For a more extensive guide to the best possible sleep, check out our longer article filled with tips on how to get the best sleep possible each night.

In the meantime, here are some important things to keep in mind about good sleep, especially when it comes to metabolism.

  • Try to avoid heavy foods right before bed. At night, your body slows down metabolic processes. Forcing it to work overtime to digest things you eat right before bed can interfere with healthy cycles of metabolism.
  • Alcohol, caffeine, nicotine, and other drugs ingested too close to bedtime will likely have a similar effect. We know these substances negatively impact our ability to sleep healthily, and we also know that many of them are directly linked to poorer metabolism functioning.
  • Exercise is a great way to improve both sleep and metabolism. Working out causes your body to consume energy efficiently, and as we mention in our article about how exercise impacts sleep, working out and sleeping create a positive feedback loop that increases our ability to do either activity. For more on how to exercise for sleep, check out our article on the best types of exercise to promote healthy sleep!

Diet and Your Sleep Quality

Written by Alex

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Man in pajamas having breakfast in bed

The average person spends a lot of time (about 30 percent of their life) sleeping. As crazy as that may seem, the third of our time we spend resting at night is incredibly important to making sure we are healthy and happy during our time spent awake. But in the same way, all of the habits and activities we engage in during the day inevitably have a big impact on how we sleep.

Some habits can be detrimental to our sleep quality and in some cases may induce insomnia or raise blood pressure, like drinking excessive amounts of alcohol, using nicotine, or ingesting caffeine late in the day. Others, like exercise and meditation, have been shown to increase sleep quality and duration.

The big picture answer is that diet does in fact play a role. Studies show that a person’s diet impacts how they sleep in a number of ways. This is likely due to the fact that what we eat directly affects important systems related to our sleep, such as brain chemistry, circulatory systems, and overall weight.

And what about popular beliefs about eating habits that harm or help sleep, like drinking milk or avoiding meals before bed? Read on to learn more about how changed to your diet can improve, or degrade, the quality of your sleep.

How diet affects sleep

Diet influences our nights the same way most other behaviors do: by causing changes to the circadian rhythm and the sleep cycle. The circadian rhythm is the body’s internal clock. An entire part of your brain is dedicated to keeping this clock running, always working to adjust our sleep-wake cycle according to external stimuli like light or sound. Some foods affect the circadian rhythm by triggering the production of chemicals in the brain that encourage or discourage sleep. Most foods that promote better sleep work in this way.

There are two main phases of the cycle: one in which your mind is more active, known as Rapid Eye Movement (REM) sleep, and a deeper sleep known as Non-REM sleep. Certain dietary habits can interrupt sleep by causing intense digestion or excess weight gain, which disrupts this cycle.

Foods that can promote sleep

Luckily for anyone interested in making changes to their eating habits to improve their sleep, studies show that a well-balanced diet is generally a good first step. A healthy diet can improve your night in two major ways: by promoting the synthesis of compounds that can improve the quality of your slumber, and by limiting the intake of foods that can interrupt it. Three chemicals, each playing a big role in the process, are significantly affected by diet:

  • Serotonin: Serotonin is a neurotransmitter that helps regulate the circadian rhythm and sleep. Scientists are still working to understand all the complexities of the roles it plays, which include stimulating both wakefulness and arousal. One scientific review of over 50 years of serotonin research explains that serotonin is involved in starting, moderating, and ending these cycles.
  • Melatonin: Melatonin is a hormone that plays an important part in regulating the circadian rhythm and promoting a restful night. Evening darkness stimulates the body to produce melatonin, which continues to build up in the brain through the night. Melatonin works in part by lowering core body temperature.
  • Tryptophan: Tryptophan is a protein hormone that is the single precursor to serotonin. That means that in order to make serotonin, the body needs tryptophan. While the hormone can be produced internally, the body can also use tryptophan that is consumed in foods we eat.

Healthy Complete Breakfast served in bedSeveral foods can increase the natural production of these compounds or introduce more for the body to use. While all foods should be consumed in moderation, a 2016 scientific review found that including or substituting the following items into your diet can stimulate your body to produce the compounds it needs for a good night’s sleep:

  • Milk: Milk products contain natural tryptophan. Several studies found that drinking a glass of milk or malted beverage before bed reduced awakenings, increased sleep time and promoted higher quality sleep.
  • Kiwis/Tart Cherries: Cherries contain melatonin and kiwis contain serotonin, among other nutrients. Studies show that people who regularly consumed these fruits had less trouble going to and staying asleep, along with an overall better quality during the night. Note, however, that too much sugar could play a negative role.
  • Whole Grains: Whole grains found in whole-wheat toast and oatmeal can trigger the production of serotonin. Johns Hopkins Medicine says that eating complex carbohydrates before bed can increase serotonin levels without burdening the digestive system late at night.

Diet habits that can degrade sleep quality

poor diet of junk food can lead to bad quality of sleep

Scientists say that a sleep-promoting diet is more about having a balanced diet than eating or avoiding specific foods. That is, diets that are unbalanced in favor of a specific food group, especially if those foods are known to be unhealthy for other reasons, are likely to have detrimental effects on sleep health. High fat, carbohydrate and protein diets, in particular, have been shown to have adverse effects on sleep health. And importantly, they all influence sleep in different ways, suggesting again that a balanced diet is important for quality sleep.

  • High-carbohydrate diet: Diets high in carbohydrates were correlated with less short-wave sleep. This type of deep sleep is part of the Non-REM phase. High carbohydrate diets do tend to improve REM when the brain needs more immediate energy for higher brain activity. But Non-REM is critical for the body to recuperate from the day, build muscle and bone, and boost the immune system.
  • High-fat diet: High-fat diets have an effect almost inverse to high carbohydrate diets. Diets with high fat reduce REM and increase the number of arousals a person experiences in a night. However, a diet high in fat can also improve Non-REM. REM is important for mental alertness upon waking, and arousals can interrupt a good night’s sleep. High-fat diets can also lead to excess weight gain, which is associated with several sleep disorders including obstructive apnea.
  • High-protein diet: High-protein diets, especially due to the consumption of meats, have been associated with negative sleep patterns. In a 2019 study, scientists suggest that a high protein intake can cause an amino acid imbalance in the body that disrupts its ability to synthesize serotonin from tryptophan. Protein is also difficult and time consuming for the body to digest, which can cause difficulty at night.
  • Spicy foods: Johns Hopkins Medicine notes that spicy and acidic foods should be avoided 3-4 hours before bed, as they can cause acid reflux that is worsened by lying down.