The evidence is convergent. Multiple independent sources reach the same conclusion, the underlying mechanism is well-characterized, and even the field's most cautious voices treat it as worth doing.
The most important ultradian rhythm for sake of this discussion is the 90 minute rhythm that we're going through all the time in our ability to attend and focus. And in sleep, we are, our sleep is broken up into 90 minute segments.
Every Sunday: the week’s new conflicts and verdict changes — and nothing else.
Native comments, Twitter mentions, and Reddit threads about this claim — surfaced together so the conversation isn't fragmented across platforms.
Bookmarking — the dossier-vs-overview split is the right call. Most of the time I want overview; sometimes I want receipts.
Would love a "what would change this verdict" RSS feed. Sign me up if it exists.
Don't expect the focus to come early, expect focus to come in the middle and then kind of taper off.
Ultradian rhythms are rhythms of about 90 minutes or so and all of our existence is broken up into these 90-minute ultradian cycles.
You may have heard of circadian rhythms. Circadian means circa, about a day. So it's 24-hour rhythms because the Earth spins once every 24 hours. Ultradian rhythms occur throughout the day and they require less time. They're shorter. The most important ultradian rhythm for sake of this discussion is the 90-minute rhythm that we're going through all the time in our ability to attend and focus.
10 minutes of bright outdoor light within the first hour of waking anchors the circadian phase and improves sleep onset that night.
Morning sunlight exposure shifts the cortisol awakening response forward, improving daytime alertness.
Long-term morning sunlight reduces age-related macular degeneration risk.
Sleep regularity predicts all-cause mortality more strongly than sleep duration.
Tracking deep sleep on a wearable accurately reflects EEG-measured slow-wave sleep.
Caffeine has a half-life long enough that consumption after 2pm measurably degrades deep sleep in slow metabolizers.