Appetite: Chrononutrition and Brain Health: The Overlooked Impact of Late-Night Eating

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Imagine if the timing of your meals could shape not just your waistline, but your mood, focus, and energy levels. Chrononutrition, the science of how food timing interacts with the body’s circadian rhythms (biological clocks), offers fascinating insights into this connection. While we understand what we eat can cause health issues, when we eat might be just as critical.

Modern eating patterns, particularly late-night snacking, disrupt the delicate balance of our biological rhythms. This not only hampers metabolism leading to physical health problems, it can also affect the brain's ability to function at its best. The result? Impaired memory, low energy, poor concentration, and a rollercoaster of moods that many of us accept as part of daily life.

To understand how these disruptions occur and why chrononutrition matters, let’s look at some of the biological processes that link food timing to brain health. The insights might just change the way you look at your next meal—and the clock.

Circadian Rhythms

Circadian rhythms are the body’s natural 24-hour cycles, regulated by an internal ‘master clock’ in a part of the brain called the hypothalamus. They are influenced by environmental cues like light and darkness and govern various physiological functions, including metabolism, hormone production, and digestion. When we have lifestyles that support healthy circadian rhythms, we can feel and function at our best. For many though, the norm is to have long days which means we end up eating late at night, well past sunset and this disrupts our metabolism.

What is Metabolism?

Metabolism refers to the chemical processes that occur in the body to convert food into energy. This energy fuels everything from basic bodily functions (like breathing) to complex activities (like thinking, learning, and memory). Metabolism consists of two key processes:

Catabolism: Breaking down food to produce energy.

Anabolism: Building and repairing tissues, including in the brain.

When this balance is disrupted, it can impair both physical and cognitive functions. This happens because our bodies are forced to process food instead of resting and repairing. This reduces our ability to feel refreshed and alert the next day. A key part of this digestive stress is caused by insulin activity.

How Insulin Works in Metabolism

Insulin, a hormone produced by the pancreas, regulates blood sugar levels by helping cells absorb glucose for energy or storage after eating. However, insulin sensitivity naturally decreases in the evening as the circadian rhythm shifts the body’s focus from digestion to rest and repair. This process is evolutionary as our ancestors rarely ate after sunset.[1] Late-night eating disrupts this balance, forcing the pancreas to release insulin when the body is less responsive. This leads to blood sugar spikes and crashes, disrupting the steady energy supply needed for optimal brain function. Over time, prolonged high blood sugar levels can strain the pancreas and increase the risk of metabolic disorders.

Metabolic disorders such as obesity, Type 2 diabetes, and cardiovascular disease are frequently discussed in relation to late-night eating, but it is equally important to recognise how these eating patterns impact brain health.

Impact of Late-Night Eating on Brain Health

Irregular glucose levels

Large swings in insulin levels can damage brain cells over time and reduce cognitive efficiency. Chronic glucose dysregulation has also been linked to neurodegenerative diseases like Alzheimer’s.

Circadian Misalignment

Late-night eating sends conflicting signals to our circadian rhythms affecting our cognitive and emotional processes.[2] This can impact brain function in several ways. [3] These include:

Impaired memory formation.

Reduced neuroplasticity (the brain's ability to adapt and learn).

Increased neuroinflammation, which contributes to ‘brain fog’ and mental fatigue.

Disrupted Sleep

Eating close to bedtime diverts energy to digestion, delays sleep onset and reduces restorative sleep stages.[4] This can interfere with:

·         Clearing brain waste products.

·         Consolidating memories.

·         Preparing for cognitive tasks the next day.

Mood Dysregulation

Late-night eating increases the stress hormone cortisol.[5] This can suppress serotonin production, which supports mood regulation. This can result in:

·         Heightened stress and anxiety.

·         Increased irritability and mood swings.

·         A higher risk of depression over time.

While late-night eating might not always cause these issues, it can worsen existing fatigue or stress. The available evidence also indicates that we can improve how we feel by eating earlier as this benefits the health of the body and the brain. The quality of your food obviously plays a role in this, but it is not the only factor.[6]

Timing is Everything

To rise, eat and sleep at the same time our ancestors did would be one way to optimise our brain health because this would honour the optimal patterns of our circadian rhythms. But who today can realistically eat their dinner by sunset?

There are ways to adopt a modified eating schedule to align with our biology to support our health:

1.      Time-Restricted Eating (TRE):

o    An 8–12-hour eating window. Examples:

§  8:00 a.m. to 6:00 p.m.

§  9:00 a.m. to 7:00 p.m.

§  10:00 a.m. to 8:00 p.m.

o    Most research points to a TRE window of 10 hours being preferable to 12 hours.

2.      Avoid Late-Night Snacking:

o    Stop eating 2–3 hours before bedtime to help the sleep hormone melatonin and digestion work in harmony. This also minimises insulin and cortisol spikes and serotonin dips.

3.      Prioritise Breakfast and Lunch:

o    Front-load your calorie intake during the day to ensure stable energy for the brain.

o    Lighter evening meals are less stressful on insulin and less disruptive to cognitive efficiency.

o    Minimise carbohydrates at night which can trigger a glucose spike.

A positive ‘side-effect’ of eating for brain health is your body and mind have greater control over weight management.

For many, abstaining from food 2–3 hours before bed may seem challenging or even unrealistic. However, small adjustments to our eating patterns can help us gradually move towards better brain health.

It’s Time to Eat for Brain Health

While late-night eating is often linked to metabolic disorders, its hidden impact on brain health deserves equal attention. Many of us struggle with low energy and poor mood throughout the day, but how often do we connect these feelings to late dinners or comfort snacks? Besides issues you may be facing in life, mistimed eating can trigger mental fatigue and mood disturbances.[7]

By aligning eating habits closer to your circadian rhythms and adopting realistic eating windows, you can enhance your mental fortitude, resilience, and cognitive function. Modern nutrition is no longer just about what you eat—it’s about when you eat.

To learn more about how we can leverage Appetite to influence brain health, or how the other senses affect your sense of wellbeing, visit Nriched Living and follow Total Sensory Wellbeing on Instagram.

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[1] Petersen, M.C., Gallop, M.R., Flores Ramos, S., Zarrinpar, A., Broussard, J.L., Chondronikola, M., Chaix, A. and Klein, S. (2022) 'Complex physiology and clinical implications of time-restricted eating', Physiological Reviews, 102(4), pp. 1991–2034. Available at: https://doi.org/10.1152/physrev.00006.2022.

[2] Liu, Y., Wang, L., and Xu, S. (2021) 'Relationship between circadian rhythm and brain cognitive functions', Frontiers of Optoelectronics, 14(2), pp. 109–124. Available at: https://link.springer.com/article/10.1007/s12200-021-1090-y.

[3] Currenti, W., Godos, J., Castellano, S., Caruso, G., Ferri, R., Caraci, F., Grosso, G. and Galvano, F. (2021) 'Association between time restricted feeding and cognitive status in older Italian adults', Nutrients, 13(1), 191. Available at: https://doi.org/10.3390/nu13010191.

[4] Mughal, Imran. (2024) 'Saturated Facts', Penguin Life, pp. 110,111.

[5] Gu, C., Brereton, N., Schweitzer, A., Cotter, M., Duan, D., Børsheim, E., Wolfe, R. R., Pham, L. V., Polotsky, V. Y., and Jun, J. C. (2020) 'Metabolic effects of late dinner in healthy volunteers—a randomized crossover clinical trial', The Journal of Clinical Endocrinology & Metabolism, 105(8), pp. 2789–2802. Available at: https://pubmed.ncbi.nlm.nih.gov/32525525/.

[6] Mughal, Imran. (2024) 'Saturated Facts', Penguin Life, pp. 120,121.

[7] Qian, J., Vujovic, N., Nguyen, H., Rahman, N., Heng, S. W., Amira, S., Scheer, F. A. J. L., and Chellappa, S. L. (2022) 'Daytime eating prevents mood vulnerability in night work', Proceedings of the National Academy of Sciences. Available at: https://doi.org/10.1073/pnas.2206348119.