# Sweet Breakfast and Morning Productivity — What Does Research Say?

![Sweet Breakfast and Morning Productivity — What Does Research Say?](https://bigmed.ge/media/serve/media/blog/original/FXnqxdmOV22s1N2mwsXuW683urKQyGvXnkIQEC44.png)

**Specializations:** Dietology

> A recent study suggests that a high-sugar, high-fat breakfast may reduce morning alertness and cognitive productivity.
>
> The study was conducted at Hyogo University and published in the journal Food and Humanity.

A recent study suggests that a **high-sugar, high-fat breakfast** may reduce morning alertness and cognitive productivity.

The study was conducted at [Hyogo University](https://www.u-hyogo.ac.jp/english/) and published in the journal [Food and Humanity.](https://www.sciencedirect.com/journal/food-and-humanity)

## **What Did Researchers Study?**

The study included **13 healthy female students**. On separate days, they consumed two types of 500 kcal breakfasts:

1. **Balanced traditional Japanese breakfast** – rice, fish, egg, vegetables, fruit
2. **Typical “fast” breakfast** – donut and sweet milk-based drink (high in sugar and fat)

Researchers measured:

- Body temperature
- Heart rate variability
- Cognitive performance
- Subjective alertness and sleepiness

### **Understanding the Autonomic Nervous System**

The autonomic nervous system regulates involuntary body processes:

- **Sympathetic system** → alertness, readiness for action
- **Parasympathetic system** → relaxation, “rest mode”

[![](https://bigmed.ge/storage/aPL9NpRyBdSygDotrrPVD76ZvQzGdfAYTOHBSl6s.png)Sympathetic system -- Parasympathetic system.png 367.75 KB](https://bigmed.ge/storage/aPL9NpRyBdSygDotrrPVD76ZvQzGdfAYTOHBSl6s.png)

The balanced breakfast increased **sympathetic activation**, linked to better alertness and cognitive flexibility.

The sugary breakfast showed **parasympathetic dominance**, associated with greater sleepiness and weaker planning performance.

### **Why Can Sugary Breakfast Make You Sleepy?**

- Sugar causes a rapid **blood glucose spike**, followed by a drop
- This fluctuation may lead to fatigue
- High-fat meals may slow digestion and affect energy stability

Although sugar can briefly increase dopamine (improving mood short-term), it does not support sustained concentration.

### **Practical Takeaway**

For better morning productivity:

Choose:

- Protein (eggs, fish, yogurt)
- Complex carbohydrates (whole grains)
- Vegetables and fruit
- Healthy fats (nuts, avocado)

## **Important Notes**

- Small sample size (13 participants)
- More large-scale studies are needed
- Individual metabolic responses vary

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Canonical: https://bigmed.ge/en/blog/sweet-breakfast-and-morning-productivity-what-does-research-say
Country: Georgia (GE), the country in the South Caucasus
Published: 2026-03-05T12:22:14+04:00
Updated: 2026-04-28T16:15:42+04:00