Will Lack of Protein Cause Insomnia? The Surprising Connection

December 15, 2025 •

4 min read

A 2025 study suggests that individuals with higher protein consumption have reduced odds of sleep problems compared to those with the lowest intake, though other research presents a more complex picture. While the direct causation is complex, a lack of protein can indeed contribute to insomnia and other sleep disturbances by affecting the body's production of key sleep-regulating chemicals.

Quick Summary

Protein deficiency can disrupt sleep through its effect on neurotransmitter production and blood sugar regulation. Inadequate intake of the amino acid tryptophan, a precursor to serotonin and melatonin, can lead to sleep disturbances. Imbalances caused by low protein may result in fatigue, fragmented sleep, and restlessness.

Key Points

Tryptophan is Key: A protein deficiency can lead to lower levels of the essential amino acid tryptophan, which is a precursor for both serotonin and melatonin, two vital sleep-regulating chemicals.
Blood Sugar Impacts Sleep: Inadequate protein can cause blood sugar fluctuations during the night, triggering stress hormones like cortisol that disrupt sleep.
Source Matters: Plant-based proteins may offer a better tryptophan-to-LNAA ratio than animal proteins, potentially improving brain absorption of tryptophan and enhancing sleep quality.
Moderate Intake is Optimal: Excessive protein intake can also negatively impact sleep by causing competitive absorption issues at the blood-brain barrier.
Supports Restorative Sleep: Low protein is associated with reduced slow-wave sleep (SWS), the deep, restorative stage of sleep.
Timing Can Influence: Consuming a light, easily digestible protein snack with some carbohydrates before bed can help stabilize blood sugar and provide a steady supply of amino acids for sleep.
Avoid Heavy Meals Before Bed: Large, high-protein or high-fat meals close to bedtime are not recommended as they are difficult to digest and can disrupt sleep.

The Tryptophan-Melatonin Pathway

At the core of the link between protein and sleep is the amino acid tryptophan. Tryptophan is an essential amino acid, meaning the body cannot produce it and must obtain it from the diet. This amino acid serves as a precursor for both serotonin and melatonin, two crucial chemicals for regulating sleep. Serotonin is a neurotransmitter that helps regulate mood and sleep patterns, and it is later converted into melatonin, the hormone that controls the sleep-wake cycle. Without sufficient dietary protein, your body may not get the tryptophan it needs to synthesize adequate levels of these sleep-promoting compounds, leading to disrupted sleep patterns and insomnia.

The Role of Blood-Brain Barrier

However, simply eating tryptophan-rich foods isn't a guarantee for a good night's sleep. To produce sleep-promoting neurotransmitters, tryptophan must cross the blood-brain barrier. Tryptophan competes for entry into the brain with other large neutral amino acids (LNAAs), which are also present in high-protein foods. A meal that is excessively high in protein can flood the bloodstream with these competing amino acids, potentially lowering the amount of tryptophan that can enter the brain and hindering melatonin synthesis. This explains why some studies show that a very high protein intake can also be associated with difficulty maintaining sleep. This delicate balance highlights why a balanced diet, rather than simply consuming more protein, is key for sleep health.

Blood Sugar and Sleep Disruption

Low protein intake can also contribute to insomnia through its effect on blood sugar regulation. Protein helps to stabilize blood sugar levels. When you don't get enough protein, your blood sugar can fluctuate more dramatically throughout the day and night. Low blood sugar, especially during the night, can trigger the release of stress hormones like cortisol, which can wake you up and make it difficult to fall back asleep. This can lead to fragmented sleep and an overall poor quality of rest. A balanced evening meal that includes a moderate amount of protein can help maintain stable blood sugar levels and promote uninterrupted sleep.

The Connection to Restlessness and SWS

Beyond just falling asleep, protein intake affects the quality of sleep, specifically slow-wave sleep (SWS), which is the deep, restorative stage of sleep. Research has found that low protein intake is linked to reduced slow-wave sleep. Conversely, consuming a healthy amount of protein has been associated with fewer episodes of wakefulness during the night. This means that even if a lack of protein doesn't completely prevent you from sleeping, it can negatively impact the restorative benefits of your sleep cycle, leaving you feeling less rested and more fatigued the next day.

How Protein Source Impacts Sleep

Recent studies have also suggested that the source of protein might play a role in its effect on sleep quality. For instance, a 2024 study indicated that protein from plant sources might be more beneficial for sleep quality compared to protein from animal sources. This is because plant proteins can present a more favorable tryptophan-to-LNAA ratio, potentially allowing more tryptophan to cross the blood-brain barrier. This does not mean animal protein is bad for sleep, but rather that a diverse diet with various protein sources is most effective for promoting overall sleep health.

Protein Sources and Sleep Quality

Here is a comparison of different protein sources and their potential impact on sleep:


Protein Source	Tryptophan Content	Absorption Speed	Potential Sleep Impact
Casein (e.g., Cottage Cheese)	High	Slow	Gradual release of amino acids supports sustained overnight sleep.
Whey (e.g., Protein Powder)	Moderate	Fast	Less ideal right before bed due to rapid absorption, better post-workout.
Plant Protein (e.g., Soy, Seeds)	Varies; some high	Varies	May offer a more favorable tryptophan ratio for brain absorption.
Lean Meats (e.g., Chicken, Turkey)	High	Moderate	Good source of tryptophan, but large amounts can be slow to digest.
Nuts and Seeds	Varies; some high	Moderate	Provide tryptophan, healthy fats, and magnesium for relaxation.

Conclusion

While a direct, one-to-one causal link between a lack of protein and insomnia is too simplistic, the connection is clear and scientifically grounded. Inadequate protein intake can deprive the body of essential building blocks for sleep-regulating chemicals like serotonin and melatonin, disrupt stable blood sugar levels that can cause nighttime awakenings, and reduce the amount of restorative slow-wave sleep. To promote better sleep, a balanced diet with moderate and varied protein intake is more effective than either a low or excessively high protein diet. Focusing on lean proteins and potentially opting for plant-based sources can help optimize the tryptophan-to-LNAA ratio and support a more restful night's sleep. As with any significant dietary change, it is best to consult with a healthcare provider or a registered dietitian to determine the right balance for your specific needs.

Outbound Link: For more detailed information on dietary influences on sleep, you can refer to insights from the Sleep Foundation.

Frequently Asked Questions

Protein provides the amino acid tryptophan, which the body uses to create the neurotransmitter serotonin. Serotonin is then converted into the hormone melatonin, which helps regulate the sleep-wake cycle.

Yes, excessive protein intake can potentially cause sleeplessness. A large amount of protein increases the level of other large neutral amino acids (LNAAs) that compete with tryptophan to cross the blood-brain barrier, which can hinder the production of sleep-promoting chemicals.

Slow-digesting proteins like casein, found in cottage cheese or Greek yogurt, are often recommended before bed. They provide a steady release of amino acids overnight, supporting sustained muscle repair and preventing overnight muscle breakdown.

A 2024 study suggests that plant proteins may improve sleep quality, possibly because they offer a more favorable ratio of tryptophan to competing amino acids. However, both animal and plant sources provide tryptophan.

Protein helps stabilize blood sugar levels. A lack of protein can lead to blood sugar drops during the night, which can cause the release of stimulating hormones like cortisol that disrupt sleep.

While turkey contains tryptophan, the sleep-inducing effect is exaggerated. The amount of tryptophan is similar to other poultry, and a full meal often includes many competing amino acids. Overall diet composition and timing play a bigger role.

A handful of almonds, a serving of Greek yogurt with berries, or some cottage cheese are all good options. They provide a source of tryptophan and can help stabilize blood sugar throughout the night.