Understanding Sleep Cycles · 04 / Put it together

Can you recognise the stages?

You have met the two sleep types. Now connect the four stages with what is happening in the brain and body.

Try a match

Choose the stage for each clue.

Use the menus, then check your choices. This is practice, not part of your quiz score.

1. The short transition from wakefulness into sleep.2. Sleep with characteristic brain patterns; often a large share of the night.3. Slow-wave sleep, when you are harder to wake.4. Rapid eye movements, active brain and often vivid dreams.

See the matches and explanations

1: N1 — the transition into sleep. 2: N2 — sleep with characteristic brain patterns. 3: N3 — deep, slow-wave sleep. 4: REM — rapid eye movements and a highly active brain.

One simplified route through a cycle.

N1Drift in
N2Settle
N3Deep sleep
N2Lighter again
REMActive brain

This is a teaching example, not a rule for every cycle. Deep sleep becomes less prominent later, and brief waking can occur. Actual nights vary.

Make a prediction

If sleep is a series of cycles, should you shorten your night to an exact multiple of 90 minutes?

Read the explanation

A cycle is not a fixed timer. Shortening your sleep to fit a calculation may simply leave you with too little sleep.