Dream Duration Calculator

Work out dream duration instantly with clear inputs, formula shown and shareable results.

About Dream Duration Calculator

REM time is the sleep duration times the REM share, and the cycle count divides total sleep by the length of one cycle. REM periods lengthen through the night, so the last cycles carry most of the vivid dreaming, which is why cutting sleep short disproportionately cuts dreams.

Formulas

REM time

REM minutes = total sleep minutes x REM share

Cycles

cycles = total sleep minutes / cycle length

Worked example

With the default values below, Dream Duration Calculator returns Time spent in REM sleep of 105.6. Change any input above and every figure here is recalculated in your browser.

Inputs used

Total sleepminimum 0.1 h: 8 h
Share of sleep spent in REMaccepts 1–60 %: 22 %
Length of one sleep cycleminimum 10 min: 90 min

Results

Time spent in REM sleep: 105.6 min
REM time in hours and minutes: 1h 46m
Sleep cycles completed: 5.33
Average REM per cycle: 19.8 min

Step by step

1Values used
2REM time
3Cycles
4Time spent in REM sleep= 105.6 min
5REM time in hours and minutes= 1h 46m
6Sleep cycles completed= 5.33
7Average REM per cycle= 19.8 min

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Dream Duration figure worked out?

REM minutes = total sleep minutes x REM share. REM time is the sleep duration times the REM share, and the cycle count divides total sleep by the length of one cycle.

Why does this matter?

REM periods lengthen through the night, so the last cycles carry most of the vivid dreaming, which is why cutting sleep short disproportionately cuts dreams.

What do I need to enter?

Enter total sleep, share of sleep spent in rem, length of one sleep cycle. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.