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Total Blackout
Pitch black
Overview
Ensuring the bedroom is completely dark. Even dim light through closed eyelids can suppress melatonin and fragment sleep.
How it works
Even dim light reaching the retina through closed eyelids can partially suppress melatonin and trigger cortisol release.
Benefits
Sleep maintenance: prevents middle-of-the-night wake-ups from light intrusion.
B
Protocol
- 1Install blackout curtains or heavy drapes.
- 2Cover or remove LED indicators on electronics.
- 3Use a sleep mask as a portable backup.
Safety Profile
Research Summary
A 2022 Northwestern study (Mason et al, PNAS) in 20 healthy adults found that a single night of dim ambient light during sleep was associated with measurable increases in nighttime heart rate and next-morning insulin resistance compared with sleeping in darkness.
Sources
Last updated: 2026-04-10
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Medical Disclaimer
This is a research summary, not medical advice. Body Signals is an independent research digest — it summarises published research for informational purposes and is not a healthcare provider. Supplements like melatonin, valerian, and magnesium can interact with prescription medications — check with your doctor or pharmacist before starting any supplement. Chronic insomnia may indicate an underlying condition (sleep apnoea, thyroid dysfunction, depression) and warrants a medical evaluation.
Need professional guidance?
If sleep issues persist despite lifestyle changes, a sleep specialist or your family doctor can help rule out underlying conditions.
Learn about sleep specialists