How long do mice sleep and when? - briefly
Laboratory mice generally rest for 12–14 hours each day, concentrating their sleep during the light period of a standard 12‑hour light/12‑hour dark cycle. Their activity peaks during the dark phase.
How long do mice sleep and when? - in detail
Mice are primarily nocturnal mammals, so the majority of their rest occurs during the light phase of a 24‑hour cycle. Typical laboratory strains spend approximately 12–14 hours asleep each day, with some individuals reaching 15–20 hours under low‑stress conditions. Sleep is fragmented into many short bouts rather than a single consolidated period.
Key characteristics of mouse sleep:
- Polyphasic pattern – dozens of episodes per day; each bout lasts from a few seconds to several minutes.
- Light‑phase dominance – 70–80 % of total sleep time occurs while lights are on; the remaining portion is distributed across the dark phase.
- Sleep architecture – non‑rapid eye movement (NREM) sleep comprises about 80 % of total sleep, while rapid eye movement (REM) sleep accounts for roughly 20 %. NREM episodes are longer than REM episodes.
- Age influence – juvenile mice exhibit longer total sleep time and higher REM proportion; adult mice show reduced sleep duration and shorter REM bouts; aged mice may experience fragmented sleep and increased wakefulness.
- Strain variation – C57BL/6 mice average 13 hours of sleep per day; BALB/c mice tend toward 15 hours; genetically altered models can deviate markedly.
- Environmental factors – temperature, cage enrichment, and light intensity modulate sleep amount and timing; cooler ambient temperatures (22 °C) promote longer sleep bouts.
- Measurement methods – polysomnography (EEG/EMG) provides precise stage identification; video tracking and infrared motion sensors offer non‑invasive estimates of bout frequency and duration.
In experimental settings, researchers often synchronize recording equipment with the light‑dark schedule (e.g., 12 h light/12 h dark) to capture the full circadian pattern. Data analysis typically reports total sleep time, percentage of NREM and REM, average bout length, and number of bouts per phase.
Overall, mouse sleep is characterized by high total duration, predominance during daylight, frequent short episodes, and a distinct balance between NREM and REM stages that varies with age, genetics, and environmental conditions.