The mouse-deer or chevrotains are the smallest of the ungulates and ruminants. They are characterized by a number of traits which are considered plesiomorphic for the Artiodactyla order. The objective of this study was to examine sleep in the lesser mouse-deer (Tragulus kanchil), which is the smallest in this group (body mass < 2.2 kg). Electroencephalogram, nuchal electromyogram, electrooculogram, and body acceleration were recorded in four adult mouse-deer females using a telemetry system in Bu Gia Map National Park in Vietnam. The mouse-deer spent on average 49.7 ± 3.0% of 24 h in non-rapid eye movement (NREM) sleep. REM sleep occupied 1.7 ± 0.3% of 24 h or 3.2 ± 0.5% of total sleep time. The average duration of REM sleep episodes was 2.0 ± 0.2 min, the average maximum was 5.1 ± 1.1 min, and the longest episodes lasted 8 min. NREM sleep occurred in sternal recumbency with the head held above the ground while 64.7 ± 6.4% of REM sleep occurred with the head resting on the ground. The eyes were open throughout most of the NREM sleep period. The mouse-deer displayed polyphasic sleep and crepuscular peaks in activity (04:00–06:00 and 18:00–19:00). The largest amounts of NREM occurred in the morning (06:00–09:00) and the smallest before dusk (at 04:00–06:00). REM sleep occurred throughout most of the daylight hours (08:00–16:00) and in the first half of the night (19:00–02:00). We suggest that the pattern and timing of sleep in the lesser mouse-deer is adapted to the survival of a small herbivorous animal, subject to predation, living in high environmental temperatures in the tropical forest undergrowth.

中文翻译：

---

睡在小鼠鹿 (Tragulus kanchil)

鼠鹿或雪佛兰是有蹄类动物和反刍动物中最小的。它们的特点是具有许多被认为是偶蹄目拟态的特征。本研究的目的是检查小鼠鹿 (Tragulus kanchil) 的睡眠情况，该鹿是该组中最小的 (体重 < 2.2 kg)。在越南 Bu Gia Map 国家公园使用遥测系统记录了四只成年鼠鹿雌性的脑电图、颈部肌电图、眼电图和身体加速度。鼠鹿在非快速眼动 (NREM) 睡眠中平均花费 49.7 ± 3.0% 的 24 小时。REM 睡眠占 24 小时的 1.7 ± 0.3% 或总睡眠时间的 3.2 ± 0.5%。REM 睡眠发作的平均持续时间为 2.0 ± 0.2 分钟，平均最大值为 5.1 ± 1.1 分钟，最长的持续时间为 8 分钟。NREM 睡眠发生在胸骨卧位，头部保持在地面之上，而 64.7 ± 6.4% 的 REM 睡眠发生在头部靠地时。在 NREM 睡眠期间的大部分时间里，眼睛都是睁着的。鼠鹿表现出多相睡眠和黄昏活动高峰（04：00-06：00和18：00-19：00）。最大量的 NREM 发生在早上（06:00-09:00）和最小的黄昏前（04:00-06:00）。REM 睡眠发生在白天的大部分时间（08:00-16:00）和前半夜（19:00-02:00）。我们建议，小鼠鹿的睡眠模式和时间适合于生活在热带森林灌木丛中的高温环境中的小型草食动物的生存，这种动物容易遭到捕食。