How much do rats sleep? - briefly
Rats typically sleep between 12 and 15 hours per day, distributed across numerous brief bouts. Their sleep pattern comprises both REM and non‑REM phases, resembling that of other mammals.
How much do rats sleep? - in detail
Rats exhibit a polyphasic sleep pattern, dividing rest into multiple bouts throughout a 24‑hour period. Adult laboratory rats typically accumulate 12–14 hours of sleep daily, with approximately 20–25 % of that time spent in rapid eye movement (REM) sleep. The remaining 75–80 % consists of non‑REM (NREM) stages, primarily slow‑wave sleep.
Key characteristics:
- Total sleep time: 12–14 hours for adult specimens; juveniles may sleep up to 15 hours, while aged rats show a modest reduction to 10–11 hours.
- REM proportion: 2.5–3.5 hours per day, occurring in short episodes of 10–30 seconds each, clustered near the onset of the light phase.
- NREM distribution: Dominated by slow-wave sleep, with episodes lasting 1–5 minutes; these episodes alternate with brief periods of wakefulness.
- Circadian influence: Sleep is concentrated during the light phase, reflecting the nocturnal activity pattern; however, rats maintain brief naps during the dark phase.
- Environmental factors: Enriched cages and reduced stress increase total sleep time by 1–2 hours; temperature extremes shorten sleep bouts.
- Species variation: Wild‑caught Norway rats (Rattus norvegicus) display slightly lower total sleep (10–12 hours) compared to domesticated strains, likely due to heightened vigilance.
Experimental observations using electroencephalography (EEG) and electromyography (EMG) confirm that sleep architecture remains stable across repeated recordings, provided lighting cycles and feeding schedules are consistent. Pharmacological agents that modulate neurotransmitter systems (e.g., GABAergic agonists) can extend REM duration, whereas stimulants such as caffeine reduce overall sleep by 15–20 %.