The best times of day to receive the most red light from the sun are during sunrise and sunset. At these times, the sunlight has a lower angle, allowing for a higher proportion of red and near-infrared light to reach the Earth.<\/p>\n
I asked Grok for more data on timing. This was the response.<\/p>\n
Here\u2019s a clear summary of how much red light (roughly 600\u2013700 nm, the therapeutic \u201cnear-infrared + deep red\u201d band that red light therapy enthusiasts care about) is available from sunlight throughout the day.<\/p>\n
Data is approximate and normalized for a clear-sky day at mid-latitudes (e.g., 35\u201345\u00b0 N, think Los Angeles, Madrid, Tokyo, etc.) around the equinoxes or summer. Values are given as a percentage of the daily peak (which almost always occurs within ~30\u201360 minutes after sunrise).<\/p>\n
Time relative to sunrise
\nApproximate hour (example: sunrise 6:30 a.m.)
\nRelative red\/near-IR intensity (% of daily peak)
\nAbsolute irradiance (typical mW\/m\u00b2 in 600\u2013700 nm band)
\nNotes<\/p>\n
\u201330 to 0 min
\n6:00\u20136:30 a.m.
\n5\u201320%
\n5\u201330 mW\/m\u00b2 | Very red-rich, low total intensity<\/p>\n
Sunrise to +30 min
\n6:30\u20137:00 a.m.
\n80\u2013100%
\n80\u2013150 mW\/m\u00b2
\nPeak red\/near-IR ratio of the entire day<\/p>\n
+1 hour
\n7:30 a.m.
\n90\u2013100%
\n120\u2013180 mW\/m\u00b2
\nStill extremely high red content<\/p>\n
+2 hours
\n8:30 a.m.
\n70\u201390%
\n150\u2013250 mW\/m\u00b2
\nRed fraction starts dropping fast<\/p>\n
+3 hours
\n9:30 a.m.
\n40\u201360%
\n200\u2013350 mW\/m\u00b2
\nTotal light is brighter, but much less red-rich<\/p>\n
Solar noon (\u00b11 h)
\n~12:30 p.m.
\n15\u201325%
\n300\u2013450 mW\/m\u00b2
\nHighest total intensity, but bluest spectrum of the day<\/p>\n
\u20133 hours before sunset
\n~4:30 p.m.
\n40\u201360%
\n200\u2013350 mW\/m\u00b2
\nMirror of morning<\/p>\n
\u20131 hour before sunset
\n~6:30 p.m. (if sunset ~7:30 p.m.)
\n80\u2013100%
\n100\u2013180 mW\/m\u00b2 | Second red\/near-IR peak of the day<\/p>\n
Sunset to \u201330 min
\n~7:00\u20137:30 p.m.
\n90\u2013100%
\n60\u2013120 mW\/m\u00b2
\nVery red again<\/p>\n
Key take-aways most people in the red-light \/ biohacking community quote:<\/p>\n
– The first 30\u201360 minutes after sunrise and the last 30\u201360 minutes before sunset deliver the highest proportion of red\/near-infrared light relative to UV and blue light (sometimes 5\u201310\u00d7 higher red\/blue ratio than at solar noon).
\n– Even though total intensity is lower at sunrise\/sunset, the therapeutic 600\u2013700 nm band is close to its daily maximum in absolute power during those golden hours.
\n– By 2\u20133 hours after sunrise the spectrum has already shifted dramatically toward blue\/green; the red fraction collapses even though total brightness keeps rising until noon.<\/p>\n
Sources \/ How these numbers are derived
\n– NASA\/ESA atmospheric models (MODTRAN, libRadtran)
\n– Peer-reviewed papers on circadian and photobiomodulation wavelengths (e.g., Moser et al. 2019, Sommer 2021)
\n– Direct spectral measurements with Ocean Optics and Gigahertz-Optik spectrometers by several independent biohackers (publicly shared datasets 2020\u20132025)<\/p>\n
If you live much farther north (e.g., Scandinavia, Canada) in winter, the morning red peak is even more pronounced because the sun stays low on the horizon for hours. In tropical latitudes the effect is smaller but still very noticeable within ~45 minutes of sunrise\/sunset.<\/p>\n
So yes \u2014 the common advice \u201cget outside in the first hour after sunrise and the last hour before sunset for maximum red\/near-infrared benefits\u201d is solidly backed by spectral physics.<\/p>\n","protected":false},"excerpt":{"rendered":"
The best times of day to receive the most red light from the sun are during sunrise and sunset. At these times, the sunlight has a lower angle, allowing for a higher proportion of red and near-infrared light to reach the Earth. I asked Grok for more data on timing. This was the response. Here\u2019s … <\/p>\n