Sleep: circadian rhythm, neurotransmitters and hormones

07/Mar/2025

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Sleep: Understanding circadian rhythm and the impact on neurotransmitters and hormones.

The Role of the Circadian Rhythm

The circadian rhythm is the body’s internal clock, regulating sleep-wake cycles based on light and darkness. When this rhythm is disrupted—due to factors like irregular sleep patterns, stress, or blue light exposure—it becomes harder to fall and stay asleep.

GABA: The Brain’s Calming Neurotransmitter

At night, cortisol levels should naturally decrease, allowing GABA—the brain’s primary calming neurotransmitter—to promote relaxation and sleep. However, if cortisol remains too high, GABA’s effect is disrupted, leaving you feeling wired but tired, struggling to unwind even when exhausted.

Two Simple Ways to Regulate Cortisol Levels

Practice Deep Breathing & Relaxation Techniques 🧘‍♀️
1. Slow, deep breathing (e.g., 4-7-8 method) can lower cortisol levels in minutes.
2. Meditation, progressive muscle relaxation, or yoga activate the parasympathetic nervous system, reducing stress and cortisol spikes.
3. Listening to calming music or spending time in nature also naturally decreases cortisol.
Balance Blood Sugar with Protein & Healthy Fats 🥑
1. Eating protein-rich meals (eggs, chicken, fish, nuts) stabilises blood sugar and prevents cortisol spikes.
2. Avoid refined carbs and excessive caffeine, which can cause energy crashes and cortisol imbalances.
3. Incorporate healthy fats (avocados, olive oil, nuts) to keep cortisol in check and support hormone balance.

These two simple lifestyle tweaks can quickly and effectively help regulate cortisol and promote a sense of calm. 😊

Blood Sugar and Staying Asleep

Most nighttime awakenings are linked to blood sugar fluctuations. If glucose levels drop too low during the night—often due to stress, inflammation, or poor metabolic flexibility—the body compensates by releasing adrenaline and cortisol, which can cause sudden wakefulness. Liver health plays a crucial role here, as it helps regulate glucose levels throughout the night.

Key Sleep-Regulating Chemicals

Beyond cortisol and blood sugar, several other biochemical messengers influence sleep quality:

Melatonin: Released by the pineal gland in response to darkness, melatonin is essential for sleep initiation. It relies on serotonin as its precursor, meaning that serotonin imbalances can impact melatonin production.
Serotonin: The Mood and Sleep Regulating Neurotransmitter
- Serotonin is a neurotransmitter primarily known for its role in mood regulation, but it also plays a crucial part in sleep, digestion, and overall well-being. It is often referred to as the "feel-good chemical" because it contributes to feelings of happiness, calm, and emotional stability.
- Serotonin’s Role in Sleep
- Serotonin is a key precursor to melatonin, the hormone that signals to your body when it’s time to sleep. When darkness falls, the pineal gland converts serotonin into melatonin, helping regulate your circadian rhythm and promote restful sleep. Low serotonin levels can lead to insomnia, difficulty staying asleep, or poor sleep quality.
How Serotonin is Produced
- Made from the amino acid tryptophan, which comes from protein-rich foods like turkey, eggs, and nuts.
- Requires healthy gut function, as about 90% of serotonin is produced in the gut.
- Influenced by sunlight exposure, exercise, and stress levels.
Serotonin and Mood
- Since serotonin influences mood, low levels are associated with depression, anxiety, and irritability, while balanced levels contribute to emotional resilience and overall mental well-being.
- Serotonin, Stress, and Sleep Disturbances
- Chronic stress can deplete serotonin levels, leading to imbalances in melatonin production, which can result in sleep disruptions. Supporting serotonin through nutrition, relaxation techniques, and lifestyle changes can improve both mental health and sleep quality.

How to Ensure a Healthy Balance of Serotonin and Melatonin

Optimize Sunlight Exposure ☀️
1. Morning sunlight (10–30 minutes daily) helps stimulate serotonin production and regulate melatonin synthesis later in the day.
2. Exposure to natural light early in the day supports the circadian rhythm and promotes healthy sleep patterns
3. Avoid bright light late in the evening, as it suppresses melatonin production.
Prioritise a Nutrient-Dense Diet 🥦(Eating the right foods helps supply the building blocks for serotonin and melatonin production.)
1. Serotonin-Boosting Foods (Rich in Tryptophan, its precursor):
  1. High-protein foods: Turkey, chicken, salmon, eggs
  2. Nuts & seeds: Almonds, walnuts, sunflower seeds
  3. Dairy products: Yogurt, cheese
  4. Legumes: Chickpeas, lentils
2. Melatonin-Rich Foods:
  1. Tart cherries (one of the highest natural sources)
  2. Walnuts, pistachios
  3. Bananas, tomatoes, grapes
  4. Oats & whole grains
3. Support Gut Health 🦠(Since 90% of serotonin is produced in the gut, maintaining gut health is crucial)
  1. Eat probiotic-rich foods: Yogurt, kefir, kimchi, sauerkraut
  2. Consume prebiotics (fiber-rich foods) to feed good gut bacteria
  3. Reduce processed foods, excessive sugar, and alcohol intake
4. Get Regular Exercise 🏃‍♀️
  1. Moderate aerobic exercise (like walking, cycling, or swimming) boosts serotonin levels.
  2. Strength training and yoga also enhance serotonin and improve sleep.
  3. Avoid intense workouts too close to bedtime, as they may delay melatonin release.
5. Manage Stress Levels 🧘‍♂️(Chronic stress depletes serotonin and disrupts melatonin) To combat this:
  1. Practice meditation, deep breathing, or progressive muscle relaxation.
  2. Engage in activities that bring joy and relaxation, such as music, reading, or nature walks.
  3. Reduce excessive caffeine, alcohol, and stimulants, as they can disrupt sleep.
6. Maintain a Consistent Sleep Schedule 🛏️
  1. Go to bed and wake up at the same time every day to regulate your circadian rhythm.
  2. Avoid exposure to blue light (phones, TVs, tablets) at least 1–2 hours before bed, as it suppresses melatonin.
  3. Use red or warm lighting in the evening to signal to your brain that it’s time for sleep.
7. Supplement Wisely (If Needed) 💊
  if diet and lifestyle changes aren’t enough, consider:
  1. 5-HTP or L-Tryptophan (supports serotonin production)
  2. Magnesium & Vitamin B6 (helps convert tryptophan into serotonin)
  3. Melatonin supplements (only for short-term sleep support)
  4. Omega-3 fatty acids (improves serotonin function)
  5. Other chemical factors to consider:
    1. Dopamine: Influences REM sleep, affecting dream cycles and cognitive restoration.
    2. Orexin: A wakefulness neurotransmitter that is regulated by insulin and circadian rhythms, helping to balance alertness and sleepiness.

Sleep Summary: A Symphony of Biochemical Signals

Sleep is not just about closing your eyes—it’s a delicate interplay of biochemical signals. A well-balanced circadian rhythm, optimal neurotransmitter function, stable blood sugar, and regulated stress hormones all work together to create deep, restorative sleep. Addressing these factors holistically is key to overcoming sleep disturbances and achieving long-term sleep health.