Light Sleep Duration
Light Sleep Duration is the cumulative time spent in sleep stages N1 and N2 during a sleep period. These stages represent transitional and intermediate sleep states between wakefulness and deeper sleep. Light sleep differs from deep sleep (N3) and REM sleep in its electrophysiological characteristics and ease of arousal. The metric captures combined N1 and N2 time; it does not distinguish between these substages or assess their continuity.
Typical Adult Ranges
% of total sleepBased on population studies. Individual needs vary by age and health status.
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Key Takeaways
Represents combined time in N1 and N2 sleep stages.
Typically comprises the largest portion of total sleep (50β60%).
Serves transitional and memory processing functions.
Defined partly as residual after deep and REM classification.
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How It's Measured
Oura estimates Light Sleep Duration by classifying epochs that exhibit sleep characteristics but lack the signatures of deep or REM sleep.
Common Influences
Total sleep duration: Longer sleep provides more time for all stages; the proportion may shift depending on when additional sleep occurs.
Deep Dive
Light Sleep Duration represents the quantity of time spent in the lighter, more easily disrupted sleep stages. It reflects portions of the night serving as transitions between wake and deeper stages, as well as interludes between sleep cycles.
A useful framing is that light sleep forms the scaffold of sleep architecture. It facilitates transitions and comprises a substantial portion of normal sleep. Light sleep is not inferior to other stages; it serves its own functions including sensory gating and memory processing. The metric indicates how much of total sleep occurred in these stages.
N1 sleep represents the transition from wakefulness, characterized by slowing brain waves and easy arousal. N2 sleep is a more stable state featuring sleep spindles and K-complexesβEEG patterns associated with memory consolidation and external stimulus blocking.
Light sleep occurs throughout the night, serving as the entry point to each sleep cycle and as bridges between deep and REM sleep. It typically comprises 50β60% of total adult sleep time, making it the largest sleep stage category by duration.