A new study has shed light on a simple habit that could energize your mornings: exposing yourself to natural sunlight for 20 minutes before waking up. Researchers from Osaka Metropolitan University in Japan found that this small change may significantly boost alertness and vitality.
The researchers explain that "dawn simulation typically involves small light sources placed on a bedside table, with a relatively low angle and directional brightness." However, any involuntary movements—like turning over or shifting positions—could lead to inconsistent light exposure during sleep, causing instability in its effects.
For the study, 19 university students aged between 20 and 30, who reported regular sleep habits—going to bed between 11 p.m. and 1 a.m. and waking up between 7 a.m. and 9 a.m.—participated in a controlled sleep lab environment designed like a bedroom. All windows were covered except for one facing east, serving as the sole source of natural light.
Researchers installed blackout curtains and a motorized device on the east-facing window, allowing them to precisely control when and how the curtains opened—slowly pulling them back at 5 millimeters per second.
Three scenarios were tested:
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20 minutes of natural light exposure before waking
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Gradual natural light exposure from dawn until wake time
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No natural light exposure
After waking up under each condition, participants were assessed for sleepiness, alertness, and fatigue. The results showed that exposure to sunlight significantly improved wakefulness and energy, helping participants feel less tired and more refreshed.
This research reinforces the idea that natural morning light can act as a powerful, non-invasive way to improve how we feel at the start of the day.
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