Why Do You Wake Up at 3 A.M.? Gut, Cortisol and Blood Sugar

Waking up around 3 A.M. can feel strangely specific. You may fall asleep normally, sleep for a few hours, then suddenly wake with a racing mind, light sleep, hunger, warmth, anxiety, or the frustrating sense that your body is "on" when it should be resting.

The truth is that 3 A.M. is not a magic time. It is usually a sign that one or more systems involved in sleep stability may be under pressure: stress hormones, blood sugar balance, alcohol or caffeine timing, reflux, sleep apnea, circadian rhythm, medications, hormones, or your gut-brain axis.

Gut health is not always the cause of nighttime waking. But gut health may affect sleep through immune signaling, microbial metabolites, tryptophan and serotonin pathways, short-chain fatty acids, and communication with the stress-response system. That is why middle-of-the-night waking is best understood as a whole-body rhythm issue, not just a bedtime problem.

Research supports a bidirectional relationship between sleep and the gut microbiome. Poor sleep may affect the gut, and changes in the gut microbiome may influence pathways related to relaxation, stress response, inflammation, metabolism, and sleep quality.

Quick Answer: Why Do You Wake Up at 3 A.M.?

Waking in the middle of the night is common and usually reflects several systems under pressure rather than one cause. The most frequent contributors are alcohol in the evening, caffeine later in the day than you think, a large or high-sugar dinner, stress and an activated nervous system, and an irregular sleep schedule. Cortisol is often part of the picture, but not because it is "too high": cortisol naturally begins rising toward morning, so if your sleep is already light, that normal rise can feel like a sudden switch flipping on. Blood sugar can also play a role, and it matters most for people with diabetes or those taking glucose-lowering medication. Gut health may contribute through the gut-brain axis, immune signaling, and microbial metabolites, though it is rarely the only factor.

The practical first steps are to move caffeine earlier, cut back on late alcohol, eat a balanced dinner earlier in the evening, keep a consistent wake time, and get morning light. If nighttime waking is frequent or severe, or comes with loud snoring, gasping, night sweats, or daytime exhaustion, speak with a healthcare professional, since conditions like sleep apnea need specific treatment.

What the Research Actually Shows

Key Takeaways

• Waking up at 3 A.M. can be linked to stress, cortisol rhythms, blood sugar fluctuations, alcohol, caffeine, reflux, sleep apnea, hormonal changes, or inconsistent sleep timing.
• Cortisol naturally rises toward morning, but stress, poor sleep, or circadian disruption may make nighttime awakenings feel more alert and harder to recover from.
• The gut microbiome may shape sleep through the gut-brain axis, short-chain fatty acids, immune balance, and tryptophan-serotonin pathways.
• Late alcohol, late caffeine, heavy meals, and high-sugar dinners can make sleep lighter and more fragmented.
• If nighttime waking is frequent, severe, or paired with snoring, gasping, night sweats, panic symptoms, or daytime exhaustion, it is worth speaking with a healthcare professional.
  

What the Science Says

Research on the microbiome and sleep is still an emerging field, but it is no longer just a wellness theory. A 2024 peer-reviewed review on gut microbiota and sleep described the relationship as bidirectional: sleep can influence microbial balance, and gut microbes may influence sleep through immune, metabolic, neural, and hormonal pathways (Lin et al., 2024, Open Life Sciences).

Another 2024 review on the gut microbiome and sleep quality highlighted several possible mechanisms, including short-chain fatty acids, tryptophan metabolism, serotonin-related pathways, inflammation, and gut-brain communication (Sejbuk et al., 2024, Nutrients).

This matters because waking up at 3 A.M. is rarely caused by one single issue. It may involve sleep architecture, stress physiology, glucose metabolism, circadian timing, digestive comfort, and gut-brain signaling working together.

For a deeper overview of how the microbiome influences sleep, see our main article on the gut microbiome and sleep.

Why 3 A.M. Wake-Ups Happen

Most people briefly wake during the night, and that is normal. The problem is when you wake fully, become alert, and cannot fall back asleep. This pattern is usually driven by a combination of factors, not a single cause, and identifying which systems are most active for you is the first step toward better, more consolidated sleep.

Common contributors fall into a few categories:

Lifestyle and timing: stress and emotional hyperarousal, alcohol close to bedtime, caffeine too late in the day, inconsistent sleep and wake times, large or spicy or high-sugar dinners, too much evening light exposure.

Physiology: blood sugar swings, reflux or digestive discomfort, hormonal changes (menopause, perimenopause), pain or inflammation.

Medical and clinical factors: sleep apnea or breathing disruption, medication effects, illness, or other underlying conditions that warrant clinician evaluation.

The Cortisol Connection: Why You Feel “Switched On”

Cortisol is often described as the stress hormone, but that is only part of the story. Cortisol is also a normal circadian hormone that helps your body wake up, mobilize energy, and respond to daily demands.

A review on the interactions between sleep, stress, and metabolism explains that cortisol is shaped by both the sleep-wake cycle and the circadian system. Cortisol tends to be lower earlier in the night and rises toward morning, which helps explain why some people feel more alert when they wake in the early morning (Hirotsu et al., 2015).

So if you wake around 3 A.M. feeling wired, cortisol may be part of the picture. That does not mean cortisol is "bad" or "too high," and it is not something to diagnose from symptoms alone. More often it means your sleep is lighter at that point in the night, your stress system is activated, or your body is responding to another trigger such as alcohol, blood sugar changes, anxiety, pain, reflux, or breathing disruption. Cortisol is usually a passenger in the pattern rather than the driver.

For more on cortisol timing through the day, see our guide to cortisol and circadian rhythm, "Cortisol, Circadian Rhythm and the Microbiome Stress Loop Explained."

Signs Cortisol or Stress May Be Part of Your 3 A.M. Wake-Up

You may notice racing thoughts, a sense of urgency or worry, feeling alert but not rested, trouble falling back asleep, jaw tension or muscle tightness, waking after a stressful day, or waking after late work, screens, or emotional conflict.

These signs are nonspecific, and they overlap with several other causes of nighttime waking, so treat them as a clue about which system to work on first rather than as a diagnosis.

The gut may be part of this pattern because the microbiome interacts with the hypothalamic-pituitary-adrenal (HPA) axis. This is one of the body's central stress-response systems, and microbiome-sleep reviews describe stress-response signaling as one possible pathway linking gut microbes and sleep quality.

This is part of what researchers describe as the stress and gut health loop: when gut-brain communication, stress hormones, and circadian rhythm are all under pressure, a normal nighttime wake-up can turn into a long, frustrating period of alertness.

How the Gut Microbiome May Shape Sleep

Your gut and brain communicate through the vagus nerve, immune signals, microbial metabolites, neurotransmitter-related pathways, and stress-hormone signaling. Scientific reviews of the gut microbiome and sleep describe these communication routes as potential mechanisms underlying the relationship among gut health, sleep quality, and stress regulation.

None of this suggests that every sleep problem starts in the gut. It means gut health can be one part of a larger sleep-regulation network that also includes the brain, nervous system, immune system, hormones, metabolism, and circadian rhythm.

1. Short-Chain Fatty Acids

Short-chain fatty acids, or SCFAs, are compounds produced when gut bacteria ferment fibers and prebiotics. They are widely studied because they help connect diet, gut bacteria, immune balance, metabolism, and brain signaling. A major review described these microbial metabolites as important messengers between the gut and the brain (Dalile et al., 2019). That same review is careful to note that the pathways are not fully worked out and that research in humans, particularly on mood and sleep outcomes, is still sparse.

For sleep, SCFAs are interesting because nighttime rest is not just a brain event. It is also connected to inflammation, glucose metabolism, gut barrier integrity, immune balance, and circadian timing. A fiber-rich diet that supports SCFA production may help create a healthier internal environment for rest and recovery.

Good sources of fermentable fiber include beans and lentils, oats, chia seeds, flaxseed, asparagus, garlic, onions, Jerusalem artichoke, green banana or plantain, and cooked and cooled potatoes or rice.

These foods do not act like sleeping pills. They support the gut ecosystem, which communicates with many of the systems involved in sleep quality.

2. Tryptophan, Serotonin, and Melatonin Pathways

Tryptophan is an essential amino acid involved in serotonin and melatonin biology. In microbiome research, tryptophan is important because gut microbes can influence how it is metabolized. A review on tryptophan metabolism and the gut microbiota described this pathway as one possible link between gut microbes and brain function (Roager and Licht, 2018).

Serotonin is often discussed in relation to mood, but it also plays roles in gut motility, gut-brain communication, and sleep-related pathways. Melatonin helps regulate circadian timing and the body's sleep-wake rhythm.

This is not the same as saying the gut directly makes you sleep. It means the gut can influence chemical pathways that help regulate calm, timing, mood, immune balance, and recovery.

Tryptophan-rich foods include turkey, chicken, eggs, yogurt, pumpkin seeds, sesame seeds, tofu, fish, and oats. Pairing these foods with fiber-rich plants may support both amino acid availability and microbial balance.

3. Immune and Inflammatory Balance

Sleep and immune function are deeply connected. When your body is inflamed, under stress, or fighting an internal imbalance, sleep can become lighter and more fragmented. At the same time, poor sleep can increase inflammatory signaling, creating a cycle that affects both gut health and rest.

The gut microbiome helps educate and regulate the immune system, and gut barrier health is central to that process. A healthy gut barrier helps keep unwanted compounds from triggering excess immune activation. Reviews of gut microbiota and sleep describe immune signaling and inflammation as important pathways that may help explain how gut health and sleep quality influence each other.

When the gut barrier is under pressure, immune signaling may increase. This does not automatically cause insomnia, but it may make the body less resilient and more reactive during the night. This is part of why people often notice worse sleep during periods of digestive discomfort, stress, illness, travel, or poor diet.

4. Circadian Rhythm and Meal Timing

Your gut microbes follow daily rhythms, and those rhythms can be influenced by when you eat, when you sleep, when you get light exposure, and how consistent your routine is from day to day. Circadian rhythm research also supports the idea that sleep, meal timing, and metabolic health are connected. A review on meal timing and circadian rhythms described how food timing can interact with clock genes, circadian hormones, and metabolic function (Pickel and Sung, 2020).

A late dinner, late-night snacking, or irregular eating schedule can send confusing timing signals to the gut and brain. Your circadian system prefers rhythm. That means morning light, consistent wake time, earlier caffeine, predictable meals, dimmer evenings, and a regular bedtime routine. These signals help your body understand when to digest, when to be alert, and when to recover.

Blood Sugar and 3 A.M. Wake-Ups

Blood sugar is another common piece of the nighttime waking puzzle. A 2023 review on sleep, diet, and glucose metabolism described a two-way relationship: sleep can affect glucose regulation, while diet, meal composition, and nighttime metabolism may also influence sleep quality (St-Onge et al., 2023).

For people without diabetes, the relationship is usually less direct. Late alcohol, a high-sugar dessert, skipping dinner, or eating a low-protein meal may affect overnight metabolic stability for some individuals. When blood sugar dips or fluctuates during the night, the body may respond by releasing hormones that help mobilize energy. That response can feel like anxiety, restlessness, hunger, warmth, or sudden alertness.

Signs Blood Sugar May Be Involved

You may notice waking hungry, sweaty, anxious, or shaky. Waking after alcohol or dessert. Waking after skipping dinner. Waking with a headache. Feeling tired or irritable in the morning.

If you take insulin or another glucose-lowering medication and you recognize this pattern, speak with your clinician rather than adjusting your dinner and waiting to see what happens. For everyone else, a gut-supportive dinner is not just about "eating clean." It should help your body stay metabolically steady overnight.

Try building dinner around protein, fiber-rich plants, healthy fats, slow carbohydrates if tolerated, and earlier timing (ideally not right before bed). Examples include salmon with vegetables and lentils, eggs with avocado and sauteed greens, turkey with roasted vegetables, Greek yogurt with chia and berries, tofu with vegetables and brown rice, or chicken with quinoa and leafy greens.

The goal is not to overeat before bed. The goal is to avoid going into the night with unstable energy signals.

Caffeine, Alcohol, and the Second Half of Sleep

Two of the most common reasons people wake in the middle of the night are caffeine and alcohol. Both can affect the second half of sleep, which is exactly when many 3 A.M. wake-ups happen.

Caffeine Can Last Longer Than You Think

Caffeine can stay active in the body for hours. Even when you do not feel wired, caffeine may still reduce sleep depth, delay sleep timing, or make the second half of the night more restless.

In a small controlled study published in the Journal of Clinical Sleep Medicine, 12 healthy sleepers took 400 mg of caffeine, roughly two to three cups of coffee, at different times before bed. Even taken 6 hours before bedtime, it measurably reduced total sleep time (Drake et al., 2013).

For people who wake around 3 A.M., moving caffeine earlier in the day may help reduce lighter, more fragmented sleep later that night.

A helpful experiment is to move caffeine earlier for two weeks. Try no caffeine after noon. Switch afternoon coffee to herbal tea. Avoid energy drinks. Watch for hidden caffeine in chocolate, matcha, pre-workout, and some supplements. If your 3 A.M. waking improves, caffeine timing may have been part of the pattern.

Alcohol Can Make You Sleepy, Then Fragment Sleep

Alcohol can make you feel sleepy at first, but it often disrupts sleep later. A review of studies in healthy volunteers found that alcohol may shorten the time it takes to fall asleep and make the first half of sleep feel more consolidated, but it increases sleep disruption in the second half of the night (Ebrahim et al., 2013).

That timing matters because many 3 A.M. wake-ups happen in the second half of sleep. This is part of why people may fall asleep quickly after wine or cocktails, then wake up around 2 to 4 A.M. feeling hot, thirsty, anxious, restless, or alert.

Alcohol may affect REM sleep, blood sugar stability, body temperature, breathing, heart rate, hydration, and stress-hormone patterns.

None of this means everyone needs to avoid alcohol completely. But if you are waking at 3 A.M., reducing alcohol or moving it earlier is one of the fastest ways to test whether it is affecting your sleep.

Is Waking Up at 3 A.M. a Gut Problem, a Cortisol Problem, or a Sleep Problem?

It may be all three, but it is usually best to think in systems. Middle-of-the-night waking rarely traces back to a single cause. Instead, it often reflects pressure on several interacting systems.

Gut-brain system. Your microbiome may influence sleep through metabolites, immune signaling, tryptophan pathways, and stress-response communication.

Circadian system. Your body expects regular timing: consistent wake time, morning light, predictable meals, and darkness at night.

Stress system. If your nervous system remains activated after work, screens, worry, or emotional stress, a normal nighttime wake-up can become a long wake-up.

Metabolic system. Late alcohol, late sugar, skipped meals, or unstable glucose patterns may make sleep lighter or more fragmented.

Breathing and medical system. Snoring, gasping, reflux, pain, medication effects, and hormone changes can all wake you up, regardless of how healthy your gut is.

This is why the best strategy is not one magic supplement. It is a sleep-stability routine.

What to Do Tonight If You Wake Up at 3 A.M.

When you wake in the middle of the night, the goal is not to force sleep. The goal is to avoid teaching your brain that 3 A.M. is a time for stress, problem-solving, scrolling, or panic. A few simple behavioral strategies, applied consistently, can help shorten how long you stay awake.

For frequent or chronic insomnia, behavioral strategies are not just sleep hygiene. The American Academy of Sleep Medicine clinical practice guideline recommends cognitive behavioral therapy for insomnia (CBT-I) as a treatment for chronic insomnia in adults, and also suggests stimulus control, sleep restriction therapy, and relaxation therapy. Notably, the same guideline advises that sleep hygiene on its own is not an effective stand-alone treatment (Edinger et al., 2021).

1. Do not check the time repeatedly. Clock-watching trains your brain to associate waking with stress. Turn the clock away or keep your phone out of reach. The more you calculate how much sleep you are losing, the harder it becomes to relax.

2. Keep the lights low. Bright light tells your circadian system that morning is coming. Use dim, warm light only if you need to get up. Avoid overhead lights, phone screens, and bright bathroom lighting when possible.

3. Avoid problem-solving in bed. If your mind starts planning, worrying, or replaying conversations, write one sentence on paper: "I will handle this tomorrow." Then return to a calming routine.

4. Try a slow exhale pattern. Breathe in gently through the nose, then exhale longer than you inhale. For example, inhale for 4 seconds, exhale for 6 seconds, and repeat for 3 to 5 minutes. Longer exhales can help shift the body toward a calmer state.

5. If you are awake too long, leave the bed briefly. Do something quiet in low light: reading something calming, gentle stretching, breathing practice, listening to quiet audio, or sitting in a chair until sleepy. Then return to bed when drowsy. This helps your brain keep the bed associated with sleep, not frustration.

6. Keep the next morning consistent. Do not sleep in for hours to make up for the wake-up. A stable wake time helps reset the next night. Morning light, movement, and a normal breakfast can help your body re-anchor its rhythm.

How to Build a Gut-Brain Sleep Routine

A gut-brain sleep routine should support digestion, circadian rhythm, relaxation, and metabolic stability. The best routine is simple enough to repeat.

Morning. Get outdoor light soon after waking. Try 5 to 15 minutes of outdoor light, a short walk, opening curtains immediately, and eating breakfast at a consistent time if that works for your body. Morning consistency makes nighttime sleep easier.

Midday. Keep caffeine earlier in the day. If you are sensitive, test a caffeine cutoff before noon for two weeks. Also try to get movement during the day, which supports metabolic health, stress regulation, and sleep pressure.

Dinner. Aim for a balanced dinner with protein, fiber, and plants. Avoid making your largest meal extremely late if you are prone to reflux, blood sugar swings, or restless sleep. A sleep-supportive plate may include one protein source, two colorful plants, one fiber-rich carbohydrate if tolerated, a healthy fat, and minimal added sugar.

Evening. Dim lights and reduce screens. Try lowering lights one hour before bed, avoiding intense work late at night, keeping difficult conversations away from bedtime when possible, taking a warm shower, reading, gentle stretching, and journaling tomorrow's tasks before bed. The goal is to lower mental activation before your first sleep cycle begins.

Night. Keep the bedroom cool, dark, and quiet. Use the bed for sleep and intimacy, not scrolling, working, or stress-planning. Helpful changes include blackout curtains, a cooler room, white noise if needed, comfortable bedding, and keeping your phone away from the bed.

Melatonin-Free Sleep Support: Where Sleepy-Biome Fits

Start with the fundamentals, because they do the most work: a consistent wake time, morning light, an earlier caffeine cutoff, less late alcohol, a balanced dinner, lower evening light, stress regulation, and a cool, dark bedroom. If nighttime waking is frequent or severe, behavioral treatment such as CBT-I has the strongest evidence behind it.

Some people also want sleep support without taking melatonin. That can be appealing because melatonin is a hormone, and not everyone wants to use it nightly. The National Center for Complementary and Integrative Health notes that short-term melatonin use appears safe for most people, but information on the long-term safety of supplementing with melatonin is still limited (NCCIH).

Melatonin may help with certain circadian timing issues, such as jet lag or a shifted schedule. It is not a sedative, so it is not necessarily the right tool for middle-of-the-night waking, particularly when the pattern is tied to stress, caffeine, alcohol, blood sugar, digestion, or sleep habits.

Sleepy-Biome is a melatonin-free option designed to support relaxation and a healthy nighttime routine. The formula includes GABA, L-theanine, 5-HTP, gut-brain probiotic strains, calming botanicals, ashwagandha, and magnesium. To be clear about what that means: it is not a cure for insomnia, it is not intended to treat medical sleep disorders, and there is no evidence that a melatonin-free formula works better than melatonin for middle-of-the-night waking. It may suit people who want a supportive nighttime routine without a hormone, alongside the fundamentals above rather than instead of them.

Check with a clinician before starting any new supplement, particularly if you are pregnant, nursing, taking medication, or managing a health condition. 5-HTP in particular can interact with antidepressants and other serotonergic medications.

When to Talk to a Doctor

Speak with a healthcare professional if nighttime waking is frequent, worsening, or affecting your daytime energy, mood, memory, or performance.

Also get medical guidance if you wake with loud snoring, gasping or choking, chest pain, night sweats, confusion, severe anxiety or panic, symptoms of low blood sugar, new symptoms after starting medication, reflux or pain or breathing problems, or daytime sleepiness despite enough time in bed.

These symptoms may point to something more than a gut or lifestyle issue. Sleep apnea, blood sugar problems, medication effects, hormone changes, reflux, anxiety disorders, and other medical conditions can all affect sleep.

The National Heart, Lung, and Blood Institute describes insomnia as a sleep disorder that can interfere with daily activities and cause daytime sleepiness. For long-term insomnia, NHLBI describes CBT-I as a 6 to 8 week treatment plan that is usually recommended as the first treatment option (NHLBI).

Getting the right evaluation can save months of guessing.

The Bottom Line

Waking up at 3 A.M. does not always mean something is seriously wrong. But it is a useful signal. Your body may be responding to stress, cortisol rhythm, blood sugar changes, alcohol, caffeine, digestion, circadian disruption, or gut-brain communication.

The gut microbiome may play a meaningful role by communicating with the brain through immune signals, microbial metabolites, stress pathways, and circadian rhythms. But gut health is only one part of the sleep picture.

The best approach is to support the whole system: stabilize your wake time, get morning light, move caffeine earlier, reduce late alcohol, eat a balanced dinner, support fiber-loving gut microbes, create a calm evening routine, and keep the bedroom cool and dark. Better sleep is not just about what happens at bedtime. It is built by the signals you send your body throughout the day.

Common Questions About Waking Up at 3 A.M.

1. Can gut health make you wake up at 3 A.M.?

Gut health may contribute indirectly. The microbiome communicates with the brain through immune signals, microbial metabolites, the vagus nerve, tryptophan pathways, and the stress-response system. But 3 A.M. waking can also come from stress, alcohol, caffeine, blood sugar changes, reflux, sleep apnea, hormones, or medications.

2. Is waking up at 3 A.M. caused by cortisol?

Sometimes cortisol is involved, but it is not the only explanation and it is not something to diagnose from symptoms. Cortisol naturally rises toward morning as part of the circadian rhythm. If stress, poor sleep, alcohol, blood sugar changes, or anxiety activate the body, that normal rise may feel like a sudden wired wake-up.

3. Can blood sugar wake you up at night?

Yes, and this matters most for people with diabetes or those taking glucose-lowering medication. Low blood sugar during sleep can cause sweating, nightmares, shakiness, anxiety, or waking tired and confused, and it needs medical attention rather than self-management. If you take insulin or similar medication and recognize this pattern, contact your care team, and do not adjust your medication on your own. For people without diabetes, late alcohol, skipped meals, or high-sugar meals may still affect overnight sleep stability.

4. What should I eat at dinner to support better sleep?

Choose a dinner with protein, fiber-rich plants, and healthy fats, eaten earlier in the evening rather than right before bed. This combination supports digestion, gut microbes, and steadier overnight metabolism. Examples include fish with vegetables and lentils, eggs with greens and avocado, tofu with vegetables, or Greek yogurt with chia and berries.

5. Is melatonin the best option for 3 A.M. waking?

Not always. Melatonin may help with certain circadian timing issues, but it is not a sedative and is not necessarily the right tool for middle-of-the-night waking. Behavioral sleep strategies, meal timing, a caffeine cutoff, reducing alcohol, and stress regulation may be more relevant for many people. NCCIH notes that long-term safety information for melatonin supplementation is limited, so it is worth discussing extended use with a clinician.

6. How long does it take to improve 3 A.M. wake-ups?

It varies quite a lot from person to person, and there is no set timeline. Some people notice a difference within a few nights of reducing alcohol, moving caffeine earlier, or eating a more balanced dinner, while circadian and gut-related changes tend to take longer. Tracking your sleep for two weeks can help you see whether a change is helping. If nothing improves, or things get worse, that is a good moment to speak with a clinician rather than keep experimenting.

Related Reading

• Cortisol, Circadian Rhythm and Microbial Timing Explained, for how the cortisol rhythm works across the full day.

• Cortisol and the Gut Microbiome: The Hidden Stress Loop Explained, on the stress and gut connection.

• Stress, Gut-Brain Axis and Sleep: Microbiome Disruption, on how stress reaches sleep through the gut-brain axis.

• Gut Barrier Science Hub: Intestinal Permeability and Leaky Gut, on the gut lining and immune signaling.

Scientific References

1. Lin Z, Jiang T, Chen M, Ji X, Wang Y.
   Gut microbiota and sleep: interaction mechanisms and therapeutic prospects
   Open Life Sci 2024;19(1):20220910
   doi:10.1515/biol-2022-0910 (Review)

2. Sejbuk M, Siebieszuk A, Witkowska AM.
   The role of gut microbiome in sleep quality and health: dietary strategies for microbiota support
   Nutrients 2024;16(14):2259 
   doi:10.3390/nu16142259 (Review)

3. Hirotsu C, Tufik S, Andersen ML.
   Interactions between sleep, stress, and metabolism: from physiological to pathological conditions
   Sleep Sci 2015;8(3):143-152
   doi:10.1016/j.slsci.2015.09.002 (Review)

4. Dalile B, Van Oudenhove L, Vervliet B, Verbeke K.
   The role of short-chain fatty acids in microbiota-gut-brain communication
   Nat Rev Gastroenterol Hepatol 2019;16(8):461-478
   doi:10.1038/s41575-019-0157-3 (Review; notes human evidence is still sparse)

5. Roager HM, Licht TR.
   Microbial tryptophan catabolites in health and disease
   Nat Commun 2018;9:3294 
   doi:10.1038/s41467-018-05470-4 (Review)

6. Pickel L, Sung HK.
   Feeding rhythms and the circadian regulation of metabolism
   Front Nutr 2020;7:39
   doi:10.3389/fnut.2020.00039 (Review)

7. St-Onge MP, Cherta-Murillo A, Darimont C, Mantantzis K, Martin FP, Owen L.
   The interrelationship between sleep, diet, and glucose metabolism
   Sleep Med Rev 2023;69:101788
   doi:10.1016/j.smrv.2023.101788 (Review)

8. Drake C, Roehrs T, Shambroom J, Roth T.
   Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed
   J Clin Sleep Med 2013;9(11):1195-1200
   doi:10.5664/jcsm.3170 (Small controlled human study, 12 participants)

9. Ebrahim IO, Shapiro CM, Williams AJ, Fenwick PB.
   Alcohol and sleep I: effects on normal sleep
   Alcohol Clin Exp Res 2013;37(4):539-549 
   doi:10.1111/acer.12006 (Review of studies in healthy volunteers)

10. Edinger JD, Arnedt JT, Bertisch SM, et al.
    Behavioral and psychological treatments for chronic insomnia disorder in adults: an American Academy of Sleep Medicine clinical practice guideline
    J Clin Sleep Med 2021;17(2):255-262
    doi:10.5664/jcsm.8986 (Clinical practice guideline)

11. National Institute of Diabetes and Digestive and Kidney Diseases.
    Low blood glucose (hypoglycemia)
    NIDDK, National Institutes of Health (Government health resource)

12. National Center for Complementary and Integrative Health
    Melatonin: what you need to know
    NCCIH, National Institutes of Health (Government health resource)

13. National Heart, Lung, and Blood Institute.
    Insomnia
    NHLBI, National Institutes of Health (Government health resource)

Written by Ali Rıza Akın

Microbiome Scientist, Author & Founder of Next-Microbiome

Ali Rıza Akın is a microbiome scientist with nearly 30 years of experience in translational biotechnology, systems biology, and applied microbiome research, spanning discovery, preclinical development, and clinical-stage translation.

His work focuses on how microbial ecosystems interact with human physiology, including:

• Gut barrier function and intestinal permeability

• Mucus-associated microbiota (Akkermansia-related systems)

• Oral–gut microbiome axis

• Short-chain fatty acids (SCFAs) and metabolic signaling

• Circadian rhythm–microbiome interactions

• Clinical Research Contributions

He has contributed to multiple clinical-stage microbiome programs, supporting bacterial strain discovery, optimization, and formulation design across different therapeutic areas, including:

Active Ulcerative Colitis (Inflammatory Bowel Disease)

Hyperoxaluria (Oxalate Metabolism Disorder)

Microbiome-driven gut health and inflammatory conditions

These studies were part of broader clinical development programs evaluating microbiome-based approaches. His contributions focused on the early-stage scientific and translational pipeline, including strain discovery, functional optimization, and multi-strain formulation design.

Scientific Contributions:

Ali Rıza Akın is the discoverer of Christensenella californii, a bacterial species associated with microbiome diversity and metabolic health.

He is a contributing author to scientific publications and Bacterial Therapy of Cancer (Springer), and the author of Bakterin Kadar Yaşa: İçimizdeki Evren: Mikrobiyotamız.

Approach:

His work emphasizes evidence-based microbiome science, long-term safety, and a systems-based understanding of how microbes influence human health.

Review and Sources

This article is written and reviewed by a microbiome scientist and is based on peer-reviewed research in sleep science, circadian biology, microbiome research, nutritional metabolism, and behavioral sleep medicine, together with guidance from the National Institutes of Health and the American Academy of Sleep Medicine. The sources are listed in the References. The goal is to explain possible mechanisms behind 3 A.M. waking without claiming that gut health, cortisol, blood sugar, or any supplement is the only cause. This article is reviewed periodically against current research.

Medical Disclaimer

This content is for educational and informational purposes only and is not medical advice. It is not intended to diagnose, treat, cure, or prevent any disease, including insomnia, sleep apnea, diabetes, or any other sleep or metabolic disorder. If you have diabetes or take insulin or other glucose-lowering medication, do not change, reduce, or skip any medication based on this article, and contact your healthcare team about suspected night-time low blood sugar, which can be a medical emergency. If nighttime waking is frequent or severe, or comes with loud snoring, gasping, chest pain, night sweats, confusion, or heavy daytime sleepiness, see a qualified healthcare professional, since these can point to a treatable condition. Dietary supplements are not reviewed or approved by the US Food and Drug Administration for safety before they are sold. Talk to a clinician before starting any new supplement, including melatonin and 5-HTP, especially if you are pregnant, nursing, managing a health condition, or taking medication, since some ingredients can interact with antidepressants and other prescriptions.

Last reviewed: July 2026