Lizards' Sleep Patterns: All-Day Snoozers Or Not?

Sleep is an essential function for all animals, and while it is easy to observe sleep in pets like cats and dogs, the sleeping patterns of reptiles are harder to pinpoint. Lizards, in particular, have diverse sleeping habits depending on their species and environmental factors such as temperature, food availability, and time of year. So, how much do lizards sleep during the day?

Lizards sleep between four and 18 hours a day

Lizards are a diverse group of reptiles, with over 7,000 species worldwide. Their sleeping habits are just as varied, with some lizards sleeping for as little as four hours a day, while others may sleep for up to 18 hours or more. This variation in sleep duration is influenced by factors such as species, climate, and resource availability.

For example, lizards in cold climates may enter a state of brumation, a less deep sleep similar to hibernation, for several months during the coldest periods. This adaptation allows them to conserve energy and survive through the winter when food sources are scarce. Similarly, desert-dwelling lizards may become nocturnal during the summer months to avoid the extreme heat, resulting in altered sleep patterns compared to their behaviour during cooler seasons.

The sleep patterns of lizards have been a subject of scientific interest, with researchers studying the bearded dragon, a popular pet lizard species, to gain insights into their sleep behaviour. These studies have revealed that lizards share similar sleep patterns with humans, exhibiting cycles of deep sleep and rapid eye movement (REM) sleep. However, lizard sleep cycles are faster and more regular, resulting in numerous shorter cycles throughout their sleep period.

The discovery of REM sleep in lizards is particularly intriguing, as it was previously believed to be present only in mammals and birds. This finding suggests that these sleep patterns may have evolved in a common ancestor of reptiles, birds, and mammals over 300 million years ago. Furthermore, it raises the possibility that even dinosaurs may have experienced REM sleep, providing a fascinating glimpse into the ancient origins of sleep behaviour.

In summary, lizards are versatile in their sleeping habits, with their sleep duration and patterns influenced by a range of environmental and physiological factors. While they may not sleep all day, their sleep patterns share similarities with humans and provide valuable insights into the evolution of sleep across different species.

Lizards sleep in cycles of deep sleep and REM sleep

Lizards have been found to have two distinct sleep states: a slow-wave stage and a REM-like stage. The slow-wave stage is characterised by low-frequency, high-amplitude brain waves, interrupted by occasional bursts of neuron activity. The REM-like stage is characterised by brain activity similar to that of an awake lizard, along with rapid eye movements.

The slow-wave stage is similar to non-rapid eye movement (NREM) sleep in mammals, and the REM-like stage is similar to rapid eye movement (REM) sleep. During the REM-like stage, lizards may experience a slight decrease in heart rate variability and muscle tone.

The two sleep states alternate with a periodicity of around 80 to 90 seconds, a regularity that has not been observed in mammals or birds. However, the presence of true REM sleep in lizards is still a subject of debate, as the expression of these sleep states differs between lizard species, and there are missing pieces of information.

Lizards sleep with their eyes closed, except for geckos

Sleep is a vital part of the 24-hour rhythm of lizards, just as it is for many other animals. Lizards, in general, sleep with their eyes closed, but there is an exception for geckos.

Geckos are the most well-known group of nocturnal lizards, although a few species are diurnal. During the day, geckos hide among bark or under palm fronds, rocks, and other cover to avoid predators. They emerge after sunset to hunt their prey, which primarily consists of insects. However, larger geckos like the tokay gecko can also feed on small lizards, birds, and frogs.

Unlike geckos, most lizards have eyelids and will close their eyes when they sleep. The only exception to this is the group of lizards known as geckos, which lack eyelids. Despite sleeping with their eyes open, geckos are still unconscious during this time.

The sleep patterns of lizards have been a subject of interest for researchers. A study on the bearded dragon, a popular pet lizard, revealed that lizards share similar sleep patterns with humans. The study found that lizards experience cycles of eye movements and deep sleep, similar to the REM and slow-wave sleep observed in humans. However, the lizard sleep rhythm is faster and more regular, resulting in numerous shorter cycles.

The diverse group of lizards, consisting of over 6,000 species, exhibits varying sleep durations. Some lizards sleep for as little as four hours a day, while others may sleep for more than 18 hours. Environmental factors, such as the time of year, temperature, and food availability, also influence their sleep patterns. Lizards in cold climates may enter a state of brumation, a less deep sleep than hibernation, during the winter months.

Lizards sleep in safe and comfortable locations

Lizards sleep in a variety of locations, depending on their size and the number of predators they have. Smaller lizards tend to seek out enclosed spaces, such as cracks and crevices, where they are safe from larger animals.

Leopard geckos, for example, spend their days hidden under rocks and other cover to avoid predators like foxes and birds of prey. They emerge after sunset to hunt. Tokay geckos, on the other hand, spend their day hidden among bark or under palm fronds, where they can thermoregulate effectively by moving between different microhabitats.

Larger lizards, such as monitors and Komodo dragons, which have few natural predators, tend to sleep in more open areas.

Lizards are also known to sleep on walls, although this is a rare occurrence. The Mediterranean house gecko is one species that has been observed sleeping under awnings and in house sidings during the day.

Lizards are cold-blooded, so they may brumate (a less deep sleep than hibernation) for several months in cold climates.

Lizards sleep at night

Lizards are a diverse group of reptiles, with over 7,000 species worldwide. While most lizards are diurnal, meaning they are active during the day and sleep at night, there are a few species that have evolved to become nocturnal, hiding during the day and emerging at night.

Diurnal lizards are typically active during the day, soaking up the sun's rays and hunting for food. As night falls, they retreat to their sleeping spots, which can vary depending on the species. Smaller lizards may seek out cracks and crevices where they feel safe from predators, while larger lizards with fewer natural enemies, such as monitors and Komodo dragons, opt for more open sleeping areas.

The sleep patterns of lizards have been a subject of interest for researchers. A study on the Australian bearded dragon revealed that lizards may share similar sleep patterns with humans, including cycles of deep sleep and rapid eye movement (REM). However, lizard sleep rhythms are faster and more regular, resulting in numerous shorter cycles compared to humans.

The amount of sleep lizards get can vary significantly, ranging from just four hours to over 18 hours a day. Environmental factors, such as the time of year, temperature, and food availability, also influence their sleeping habits. Lizards in colder climates may enter a state of brumation, a less deep sleep than hibernation, for several months during winter.

Nocturnal lizards, such as geckos, desert night lizards, and prehensile-tailed skinks, have adapted to be most active at night. They spend their days hidden from predators, often under rocks or palm fronds, emerging after sunset to hunt for food. These lizards have developed unique strategies to regulate their body temperatures effectively, even when they are not exposed to direct sunlight.

Frequently asked questions