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Turtles are fascinating and highly adaptable. They take advantage of both the dry land and the sea to meet their needs. When they aren’t eating or swimming, they come out of the water to bask in the sunlight. Turns out that turtles meet their vitamin D needs through sunlight exposure.
They’ve also evolved multiple mechanisms for breathing both outside the water and underwater. They’re the oldest reptile species in the world, dating back to the time of the dinosaurs, so they must be doing something right.
As pets, they’re playful, interactive with their owners, but usually mellow and quiet. Many owners are surprised by how quickly their pet turtle opens up and gets attached to them. There are lots of interesting things to say about these animals.
From questions such as “what’s the difference between turtles and tortoises” to “how do turtles float and breathe underwater”, it’s pretty clear that turtles are still enigmatic animals for many. Indeed, there’s always something new to learn about them.
I’ve already written a few articles about turtles, including those where I answer the questions above. Another topic of interest I’ve wanted to cover is a turtle’s sleeping habits. Have you ever wondered if turtles can sleep underwater, or how exactly their sleeping habits differ from other animals?
Well, I’m going to share some info on that in today’s article. So, let’s see the “how”, the “when”, and the “where” about turtles’ sleeping habits.
How Much Do Turtles Sleep?
This is a question with no single answer. Depending on the species, the sleeping hours might differ quite a lot.
On average, sea turtles sleep around 4-7 hours a day. The sleeping window might sometimes extend to 9 hours or more, depending on environmental factors and the turtle’s age. The turtle’s species also makes a difference in sleeping patterns. Certain turtles like the Green Sea Turtle, sleep for about 10-11 hours a day, year-round! It seems that turtles aren’t universally early birds nor late sleepers.
Younger turtles sleep the least amount of time. That comes up to 4 hours at most, often less. Because they’re still growing, younger turtles have a high metabolism and they prefer keeping active throughout the day.
Older turtles consume less energy and tend to sleep longer. The older the turtle, the more it sleeps. The weather also makes a difference. When the temperatures rise and the sunlight is abundant, a turtle’s sleeping cycle shortens. Subsequently, on chilly, gloomy days, turtles usually prefer sleeping in.
The longest sleeping period for turtles lasts for 2-6 months. This long sleep takes place when temperatures drop considerably and food becomes scarce, usually between October and February.
To survive the harsh living conditions and to conserve energy, turtles go into long periods of sleep to lower their metabolic rates. Fun fact! While this process is usually called hibernation, the term used for the long periods of deep sleep in cold-blooded reptiles is “brumation”.
Are Turtles Nocturnal or Diurnal?
Nocturnal animals are wide awake at night and fast asleep during the day. Some examples of nocturnal animals include owls, bats, hedgehogs, and foxes. Conversely, diurnal animals are active during the day, and they get their Zzz’s at night.
Most animals you can think of are diurnal, including mammals, birds, and most primates. A lot of people believe humans are diurnal animals, but many night owls like myself would disagree. But back to turtles now. Where do they fit in here, you may ask? Drumroll…
Turns out that turtles are diurnal animals! You’ve probably guessed it already. Turtles start hibernating when temperatures drop and daylight time grows shorter. Turtles also need direct sunlight exposure to metabolize vitamin D3.
They regulate their body temperature via external factors, and they generally need pretty high temperatures, between 24-30 degrees Celsius. This means turtles are most active during the daytime.
Certain turtle species might exhibit nocturnal activity. The Green Turtle is such an example. While they are most active during the day, researchers have observed that in nature, Green Turtles also engage in feeding, nesting, and mate searching activities at night. However, despite their nocturnal activity, Green Sea Turtles aren’t a nocturnal species.
Can Turtles Sleep Underwater?
Yes, turtles sleep wherever they feel safe and comfortable, even underwater. It doesn’t matter if it’s on the shore, in their favorite basking spot, or underwater.
But how do they sleep for 4-7 hours underwater? Most turtles need to come back up for air every few minutes to an hour. At least that’s the case for when they’re awake. So, what sort of dark magic takes place when they sleep submerged for hours on end?
It’s a combination of two main factors. Turtles are bimodal breathers. This means they’re able to uptake oxygen both underwater and on dry land. They do so through different mechanisms. When outside of the water, turtles breathe the air in through their nostrils. Their lungs fill up with oxygen, and they can hold their breath for up to one hour when underwater.
Depending on the species, they also have different modes of oxygen uptake when underwater. Some turtles use pharyngeal breathing, while others exchange gases through their cloaca.
Then, because most species can’t meet their full oxygen needs through secondary breathing methods, they usually go into a state of deep sleep. This makes their metabolism drop drastically and leads to lower oxygen requirements.
Do Turtles Need Light at Night?
No, not really. Turtles naturally go to sleep when the sun goes down. They feel most relaxed and ready to sleep when brightness drops to a minimum. Just like in humans, light exposure late at night can mess up with a turtle’s sleeping cycle.
But it’s even worse for turtles. Unlike humans, who use other clues to determine their sleeping schedule, turtles are entirely dependent on environmental factors such as heat and light. That’s how they regulate their internal clock. Both harsh lighting and high temperatures will interrupt your pet’s sleep.
It’s best to turn off all lights at night if you want your turtle to sleep properly. This also includes other lights in the room, not just the ones used for the enclosure. Any source of environmental brightness can irritate your turtle’s eyes and lead to sleeping problems.
If you rely on your UVB lamp to keep the enclosure warm, you might want to look for other options for nighttime. You can try a night viewing light, like a moonlight heating lamp. Infrared lights are another great option to keep the enclosure warm without harsh light disrupting your turtle’s sleep.
Can Turtles See in the Dark?
Yes! Turtles can see pretty well in the dark, at least by our standards. Like humans, turtles don’t have a tapetum lucidum. This weird concoction of words might sound like a Harry Potter spell but bear with me. The tapetum lucidum is actually a scientific term. It refers to a special light-reflecting membrane situated behind the retina. It’s responsible for the excellent night vision of animals such as cats, dogs, raccoons, and owls.
It’s also the reason behind those creepy shiny eyes caught in cat photos. Without a tapetum lucidum, true night vision isn’t possible. Therefore, just like in humans, a turtle’s eyes will take a while to adjust to the darkness once the light is turned off. Once their eyes adjust turtles can see most objects in their immediate surroundings. When the light is suddenly turned back on, their eyes have to adjust back to light vision.
Speaking of how turtles’ eyes work, did you know scientists are now speculating that turtles can see more shades of red than us humans? That’s because researchers have discovered that turtles carry the CYP2J19 gene, just like birds. Thanks to this gene, birds and turtles convert yellow pigments in their food into red, which also makes its way into the retina, contributing to the heightened red-spectrum vision.
Do Turtles Sleep with Their Eyes Open?
For the most part, no. From the information I’ve gathered, turtles sleep with their eyes closed. They specifically do that to shut out irritating light. But even when it’s already dark outside, turtles will still sleep with their eyes closed.
Turtles might also close their eyes when relaxing in their basking spot or when resting. Closing their eyes also helps them relax their muscles. So, sometimes, when a turtle’s just drifting through the water or laying in the sunlight with its eyes closed, it might not be sleeping.
Oh, and by the way, turtles are among the few animals on earth that have well-developed eyelids! It would be a total waste to have perfectly functional eyelids and not use them, right?
But turtles’ eyelids aren’t just useful sun blockers and sleeping aids. They also protect their eyes from dust, wind, and other irritating factors. Turtles also have a transparent third eyelid called the nictitating membrane. This eyelid shuts horizontally and it’s used to protect and moisten the eye without diminishing an animal’s sight.
Can You Sleep with Your Pet Turtle?
So, a turtle sleeps up to 6 hours on average. It breathes very well outside the water and it doesn’t need any special UV light during the night. Great! That means it would sleep just as well on your bed. So, can you sleep with your pet turtle then? Heck no!
Well, actually you could. Nobody’s stopping you. But it’s a pretty risky idea for multiple reasons. You should really think twice before cuddling up in bed with your turtle.
Keeping your turtle in bed or anywhere outside its tank is actually dangerous to your health. Whether caught in the wild or kept in captivity since they were little hatchlings, turtles carry dangerous salmonella bacteria on their skin and shells.
Salmonella infection in humans often leads to nausea, vomiting, and diarrhea, and the symptoms can even last up to 3 days. Children, elderly people, and people with weakened immune systems can develop life-threatening infections, often requiring urgent hospitalization.
Letting your turtle sleep in your bed can also pose a threat to its safety. You never know whether your turtle will accidentally fall off the edge of the bed. You might also push or knock your pet off the bed in your sleep.
In either case, if your turtle falls off an elevated surface, shell damage is a given. This type of injury, depending on its severity, can take months to heal. Shell damage also predisposes your turtle to infections.
Last but not least, the temperature outside the enclosure might be unsuitable. If the temperature falls too low during nighttime, this negatively impacts the turtle’s health and immune system over the long term. Temperatures below 22 degrees Celsius are not uncommon at night, especially if you sleep with your window open.
There you have it! A turtle’s sleeping habits aren’t that weird if you think about it. Turtles are diurnal animals and they sleep anywhere between 2-11 hours a night. They sleep with their eyes closed, and they get the best rest in a dark, quiet environment.
Turtles never cease to amaze us with their weird quirks, but this time around, it seems they’re acting in more familiar ways than we would’ve thought.Turtles