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This older Kefiw page is kept for reference, marked noindex, and removed from the primary sitemap. The current Kefiw experience is focused on property decisions: cost, quotes, damage, buying, selling, owning, and packets.

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REM-Sync · Sleep Cycles

Sleep or wake at the end of a 90-min cycle, not mid-REM.

A full sleep cycle runs ~90 minutes. Waking at the end of a cycle (light NREM) feels rested; waking mid-REM or deep NREM feels groggy. Five to six cycles is the performance target.

Part of: Biological Maintenance

Start below
Fields marked optional can be skipped; results update as you type
REM-Sync · 90-min Cycle Timing
Initiate shutdown at
3 cycles
02:16
4h 30m before wake
4 cycles
00:46
6h before wake
5 cycles
23:16
7h 30m before wake
OPTIMAL
6 cycles
21:46
9h before wake
OPTIMAL
7 cycles
20:16
10h 30m before wake
Verdict
To wake at 07:00, initiate shutdown at 23:16 (5 cycles) or 21:46 (6 cycles).
Cycle length
90 min
Sleep latency
14 min
Optimal span
7.5–9h
Minimum viable
4.5h · 3 cycles
Formula: Wake = Sleep + (90 min × n) + latency · reversing gives bedtime for a target wake. Individual cycle length varies 70–120 min.

How to use

  1. Pick mode — wake at a target time, sleep at a target clock time, or sleep now.
  2. The tool lists 3–7 cycle windows with recommended bedtimes or wake times.
  3. Optimal windows (5 or 6 cycles) glow cyan.

Examples

Wake at 6:30 AM
Optimal sleep: 9:36 PM (6 cycles) or 11:06 PM (5 cycles). Add ~14 min sleep latency.

Before you act on the result

Health-related tools are educational planning aids. They can make a number or assumption visible, but they do not diagnose, treat, prescribe, or replace clinician guidance.

If the result points to risk, symptoms, medication questions, or urgent changes, use it as a note for a qualified professional rather than a final decision.

Next up

REM broken? Burnout is the downstream result.Burnout Monitor →

Frequently asked questions

› Does cycle length vary?

Yes — 75 to 110 minutes, individual and age-dependent. 90 min is the population mean used by most sleep studies.

› What if I can't sleep 5+ cycles?

End on a full cycle. Three complete cycles (4.5 h) feels better than four partial ones (5 h cut mid-REM).

Tips & related reading

See the Biological Maintenance hub →

Tips & how-tos

Relevant links

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