Could Eating More Fibre Improve Deep Sleep?

Does your diet today shape your sleep tonight?

Fibre is well known to aid digestion, but a recent article in New Scientist highlighted that it might also improve how well you sleep.

A recent (not yet peer-reviewed) study analysed over 4,800 nights of real-world data based on over 3,500 adults in Israel. Day-to-day dietary choices, especially fibre intake, had measurable effects on sleep quality (Shkolnik et al. 2026).

Researchers tracked participants’ food intake using food diaries and sleep data using a wearable tracker to explore how nutrition affected sleep architecture. Higher fibre intake and more plant-diverse meals were linked to lower nighttime heart rate (a sign of better recovery), as well as more deep and REM sleep. Read on for more details...

Fibre-rich foods

could Fibre and plant diversity support deeper sleep?

Higher fibre density was consistently associated with small but meaningful improvements in sleep architecture:

• +0.59 percentage points deep sleep (the most physically restorative stage, with the strongest anti-inflammatory properties)

• +0.76 percentage points REM sleep  (important for memory and emotional processing)

• −1.35 percentage points light sleep

  
  

At the same time, higher fibre intake was linked to a lower average nocturnal heart rate (−1.14 bpm), an indicator of improved overnight recovery.

Similarly, diets with greater plant diversity and higher intake of whole plant foods were associated with reductions in nighttime heart rate (−0.72 to −0.94 bpm).

This study adds to a growing body of evidence showing increasing fibre intake can have positive effects on your health. For example, a recent study in Nutritional Neuroscience, suggested that fibre intake is associated with a lower risk of dementia - this may partly be due to improved toxin removal during deep sleep.

How does Meal timing affect sleep duration and physiology?

When people ate heavier evening meals, they tended to sleep longer. This suggests that late, larger meals may extend sleep opportunity while simultaneously increasing metabolic activity during the night, potentially reducing the depth of physiological recovery.

Another takeaway: heavier evening meals were linked to slightly longer sleep, about 7.7 minutes more on average. But this also came with a trade-off, nocturnal heart rate increased by +0.73 bpm, suggesting the body may be working harder overnight. 

So while late dinners might make you feel sleepy, they may not support optimal recovery.

Do Macronutrients matter more or less than fibre for sleep?

One of the more surprising findings: short-term changes in macronutrient distribution (carbs vs fats vs protein) and micronutrient intake showed no consistent relationship with sleep outcomes.

This challenges the common focus on macro “optimisation” and instead highlights overall dietary patterns, particularly plant-forward eating, as the more relevant factor for sleep.

How Bigger dietary shifts can have a bigger effect on sleep?

When researchers looked at more extreme day-to-day dietary differences, the effects became stronger while remaining consistent in direction. In other words, the more you shift toward a high-fibre pattern, the more noticeable the sleep benefits.

What does this mean in practice so you can improve your sleep?

These findings suggest that sleep is influenced by so many factors, including what you ate yesterday. If you are looking to naturally improve your sleep, you could:

• Increase fibre intake (whole grains, legumes, vegetables)

• Eat a wider variety of plant foods

• Be mindful of large, late evening meals

  
  

Fibre-rich, plant-forward meals could be a small but meaningful step toward deeper, more restorative sleep.