Sleep is a strange thing, but we spend a lot of time doing it. Almost 1/3 of our lifetimes are spent in slumber, in fact. So, since we spend so much time doing it, it’s a good idea to learn a little more about it! Here are five weird facts about sleep you may not know.

1. Dreams may actually be guides

But not in the way your fortune cookie or astrologist tells you they are. Your brain uses your dreams to process events, newly learned skills, and even help predict and practice for future events. When you’re asleep, your brain isn’t resting; quite the opposite actually. Brain scans of sleeping individuals show predictable patterns of activity, and during the final stage of sleep (called REM sleep for the rapid-eye movement that occurs during it) your brain lights up in a way that creates vivid, sometimes nonsensical, dreams meant to help you sort through problems and complicated emotions in a realistic and risk-free setting.

2. Early to bed? You may be sleep deprived

Getting to sleep quickly is sometimes seen as a great blessing (especially by bleary-eyed parents and overworked employees), but it may actually be a sign that you’re sleep deprived. Generally, falling asleep should take between 10 to 15 minutes. This usually indicates your body is tired, but not completely and utterly exhausted.

Of course, the opposite also is true: if you take longer than 20 minutes to fall asleep, don’t roll around in bed. Get up, and go relax in a different room (but keep that TV off and that book closed — extra stimulus can make it even harder to sleep).

3. Sleeping with the fishes

Fish, birds, and even the northern fur seal all sleep a little differently than humans. While humans sleep with their entire brain, some animals actually only sleep in alternating hemispheres of the brain. This is assumed to be mostly for survival — by keeping one hemisphere active at all times, it allows animals to be aware of predators, surface above water if they need oxygen (such as in many marine mammals), and even to continue flying during migration. Birds have even been literally shown to sleep with one eye open, usually corresponding to the hemisphere of the brain that’s still awake.

4. Sleeping position shows personality

Actually this one isn’t true. Like a lot of hoaxes, though, it has spread across the internet like wildfire and even made it into mainstream news sources. While many cite that research has shown sleeping in the fetal position means you have a “gruff exterior, but warm open heart” or that sleeping in a star position means “you’re a good listener,” the hoax was actually the result of an informal survey done by a hotel chain. So what does your sleeping position actually mean? Probably very little — other than the possibility that one spot in your mattress may be less comfortable than another. If it’s time to find a new one, check out our line of ComforPedic mattresses. They score well against competitors, and the 10 Year warranty means you’ll have plenty of time to learn to change your sleep position if you don’t like what it says about your personality – or how it causes you back pain and snoring.

5. We don’t know why we sleep

Despite all the research done into it, we’re still not really sure why we sleep. While the effects of not sleeping are well-documented — usually hallucinations, loss of memory and language capability, the inability to plan, and even death — the evolutionary purpose of sleeping is still hotly debated. What scientists do know is that basically every animal sleeps, down to very simple creatures like nematodes and fruit flies. The effects of sleep deprivation also seem to be a constant, with decision-making and learning capabilities being the easiest behaviors to see a significant drop in. So, while we don’t know why we do it, we do know that it’s important to do!