What are our bodies actually doing while we're sound asleep? If you have no freaking clue, you're not alone. Luckily, British bed company Dreams broke down an eight-hour night of sleep, stage by stage, in a handy infographic that highlights some of the most important (and the weirdest) things our bodies do every night.For starters, you cycle through four distinct "stages" of sleep throughout the night. (Technically, there are five stages , but stages three and four are very similar, according to The National Sleep Foundation.) The first stage lasts only briefly and consists of very light sleep, while the second stage signals the full onset of sleep, during which time your body temperature drops, your breathing and heart rate become regular, and you become less aware of your surroundings.Although you spend about 45% of your night in stage two, you sleep the most deeply during stages three and four, which only take up about 25% of the night. This is also when your body gets really busy — more blood flows to your muscles, tissues grow and repair themselves, and hormones, including those that promote growth, are released. In other words, your energy levels are being restored while your body recovers from the previous day. Luckily, it's really hard to wake you up from this stage.The final stage of sleep is what we call REM sleep , which occurs about every 90 minutes. At this point, your brain is active but your muscles are completely turned off. You start to dream , your eyes move rapidly (REM stands for Rapid Eye Movement), and your body relaxes.Check out the full infographic, courtesy of Dreams, for more.