Does light help reduce sleep inertia?
It may help you feel more alert, but the evidence is thin: of two studies on bright light right after waking, one found people felt more alert and neither found better performance. Light is still the strongest signal to your body clock.
The science
Light has the biggest influence on your circadian rhythm (NIGMS), and morning light helps keep your body clock aligned with the time you get up. On sleep inertia itself, the evidence is limited: of two studies on bright light right after waking, one found people felt more alert, and neither found a clear improvement on performance tests (Hilditch & McHill, 2019).
Practical tactics
Open the curtains immediately. Use a sunrise alarm clock or a light therapy lamp. Step outside soon after waking. All of these are easy ways to get light early.
Combine with action
Light is easiest to get once you are out of bed. ByeBed's sky photo mission, for example, only counts once you have photographed the sky, so you end up at a window or outside.
Sources
- Hilditch & McHill, Nature and Science of Sleep, 2019. Sleep inertia: current insights
- National Institute of General Medical Sciences (NIH). Circadian Rhythms fact sheet
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