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Sleep, decoded
Articles built from peer-reviewed research and the published guidelines of the CDC, National Sleep Foundation, and AASM.
- Bedtime planningMay 8, 2026 · 9 min
What Time Should I Go to Bed if I Wake Up at 6 AM?
For an adult who wants to wake at 6:00 AM feeling refreshed, the best bedtimes are 9:00 PM (6 cycles, 9 h) or 10:30 PM (5 cycles, 7.5 h). Here is exactly why — and what changes for kids, teens, and seniors.
- Sleep scienceMay 8, 2026 · 11 min
The 90-Minute Sleep Cycle: The Science Behind Why It Works
Sleep cycles last about 90 minutes — but they aren’t identical, and not everyone’s clock runs at exactly 90. Here is what polysomnography studies show about the four stages, ultradian rhythms, and why timing your alarm to a cycle boundary changes how you feel.
- Sleep qualityMay 8, 2026 · 10 min
Why Am I Tired Even After 8 Hours of Sleep?
Eight hours doesn’t guarantee rest. Most people who feel exhausted after a full night woke mid-cycle, slept fragmented, or hit one of seven specific causes. Here’s the diagnostic order to check, with what to do about each.
- Bedtime planningMay 8, 2026 · 10 min
Best Bedtime for Teenagers, by School Start Time
Teenagers need 8–10 hours and their internal clocks run 1–2 hours later than adults’. For a 7:30 AM school start, that means lights-out by 9:30–11:00 PM. Here is the table by school time, the science, and what works for parents.