When do mice sleep, at night or during the day? - briefly
Mice are nocturnal creatures; they spend the majority of daylight hours sleeping and become active after dark. Their sleep cycles consist of multiple short bouts throughout the day, totaling roughly 12–14 hours of rest.
When do mice sleep, at night or during the day? - in detail
Mice are primarily active during the dark phase and rest during daylight. Their circadian system aligns peak locomotor activity with night-time, while the light period is dominated by sleep bouts. In laboratory settings under a 12 h light/12 h dark cycle, mice typically begin sleeping shortly after lights turn on, maintain prolonged sleep periods throughout the day, and awaken near the onset of darkness.
Sleep in mice consists of alternating NREM (non‑rapid eye movement) and REM (rapid eye movement) stages. An adult laboratory mouse averages 12–14 hours of sleep per 24‑hour cycle, with about 70 % NREM and 30 % REM. NREM episodes are longer and more frequent during the light phase; REM episodes cluster toward the end of the rest period, often occurring just before the transition to activity.
Environmental cues influence the pattern. Constant darkness shifts the activity phase, but mice still display a subjective “night” in which they are more active. Conversely, exposure to continuous light reduces total sleep time and fragments sleep architecture, indicating that the light‑dark cycle is a strong regulator.
Species differences exist. Wild house mice (Mus musculus) exhibit similar nocturnal tendencies, though seasonal variations in daylight length can modify the proportion of sleep versus wakefulness. In contrast, some rodent species, such as the degu, are diurnal and display opposite timing.
Key points summarizing mouse sleep timing:
- Predominant sleep occurs during the light period.
- Total daily sleep: 12–14 hours, mainly NREM.
- Activity spikes at night, with brief awakenings interspersed in the rest phase.
- Light exposure is essential for maintaining the typical nocturnal sleep‑wake pattern.