How do animals sleep if they are being hunted?

On a rainy night when I was in the comfort of my bed, I was staring at the river beside my house and started to wonder about the birds, lizards and creatures - do they ever get a restful sleep?

To begin with, it turns out that some animals do not need that much sleep as us humans. It seems that animals have adapted to how much sleep they need depending on their habitat and danger. For example, koalas sleep for up to 22 hours a day while horses and elephants need as little as 2-4 hours only. I think that maybe

the ‘nearer’ they are to danger tend to sleep less.

Animals also do not need one long session to sleep, but instead take many small naps throughout the day. Herd animals like deer and giraffes take brief naps of 5-30mins each time, this plus being in a herd helps them detect predators throughout the day and night. They are also light sleepers, meaning they don’t shut off like we do and they still listen out for that rustle in the bush.

Even more amazingly, some animals like dolphins and whales sleep ‘half-way’, where only half their brains (and eyes, ear, etc) shut off and the other side stays alert. This also helps these marine animals continue to breathe while resting their brains!

I’m glad I can have my unbroken sleep and be in the comfort of my room even during thunder storms.