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Impact of daily diet on sleep quality
This observational study used a causal-inference framework to examine whether ordinary day-to-day differences in dietary intake are associated with sleep physiology that same night, drawing on 4,793 person-nights of matched real-time food logging and multi-stage wearable sleep monitoring from 3,598 predominantly healthy adults in an Israeli cohort.
Investigators evaluated 32 dietary exposures — including fiber density, plant diversity, whole-plant food intake, a phytochemical-rich food index, evening energy load, macronutrient distribution, and individual micronutrients — against sleep architecture, total sleep time, wakefulness after sleep onset, and nocturnal heart rate.
Higher fiber density showed the clearest signal, with associations that same night of +0.59 percentage points more deep sleep, +0.76 percentage points more REM sleep, −1.35 percentage points of light sleep, and a nocturnal heart rate 1.14 bpm lower on average, while greater plant diversity, higher whole-plant food intake, and the phytochemical index were also linked to lower nocturnal heart rate.
Heavier evening meals were associated with approximately 7.7 additional minutes of total sleep but a 0.73 bpm higher nocturnal heart rate — indicating that longer sleep does not automatically equate to better sleep — and 25 of 32 dietary factors did not show robust associations after correction for multiple comparisons, positioning fiber, overall plant-food quality, and the timing of energy intake as the diet features most consistently linked to same-night sleep physiology. [NPID: diet, sleep quality, fiber, plant diversity, meal timing, nocturnal heart rate, sleep architecture, REM sleep, deep sleep, wearable monitoring, causal inference, diet-sleep relationship]
Year: 2026
