Sleep is quite a sexy topic these days. On the one hand, this is great. It’s about time we pay attention to the 33 percent of our lives that supports our daytime functioning. On the other hand, the sheer volume of information can be a bit overwhelming: a quick Google search for “sleep” yields about 900 million results. And with our increasingly busy lives, how can you possibly keep up and know what’s important to know about sleep? In this piece, I’m going to tell you three things you absolutely need to know about sleep, based on the latest scientific and medical research available.

Sleep Duration

Maybe because this is the “easiest” one to focus on and quantify for most people, the number of hours of sleep gets a lot of attention. The vast majority of adults need between seven to nine hours of sleep per night for optimal performance. There are some people who need less and some who need more, but seven to nine hours is a good rule of thumb. There are ways to determine how much sleep you actually need personally, but that will have to be addressed in a future post to keep this one reasonably short!

Also keep in mind that it is easy to misjudge how sleep deprived you actually are. As Dr. Matthew Walker, PhD, from UC Berkeley says, it’s a bit like someone at a bar who has had seven drinks — he may think he can handle another drink or two, but is probably not the best judge of his own sobriety. Sleep deprived people also sometimes are unable to tell how tired they are, because sleep deprivation actually impairs your ability to judge how sleepy you are.

Sleep Quality

And while the number of hours of sleep you get is very important, there is more to consider. Let’s say you are prioritizing sleep enough to log eight hours per night. But what if you are tossing and turning, snoring like a chainsaw, grinding your teeth, or have jittery legs that disrupt the quality of your sleep each and every night? You don’t have to be a sleep doctor to know that anything that interrupts your sleep is going to affect the quality of your sleep. Yet, up to 70 million Americans have a medically-recognizable sleep issue that prevents them from optimizing their sleep quality. If you want to optimize your sleep, you simply need to do the work to rule out any sleep disorders.

And if you are lucky enough to have no medically-recognizable sleep issues, then there’s the issue of sleep hygiene. This refers to making sure that your habits are sleep-friendly, such as optimizing the intake of any caffeine or alcohol, getting regular exercise, avoiding heavy dinners, and so on. Experts also agree that your bedroom needs to be dark, cool (about 65 degrees Fahrenheit or so), and quiet. Good sleep hygiene habits are beneficial for everyone — sleep disorder or not — kind of like how you need to brush your teeth even if you have no cavities.

In a way, it is also like nutrition. It is not enough to just get the right amount of calories per day. There’s the quality of the food, the variety, different nutrients, etc. Just like all calories are not created equal, all sleep is not created equal. People who are serious about nutrition look long and hard at what they consume, and with sleep, it’s a similar situation. Indeed, the world’s top athletes have realized that sleep impacts performance, and have started to hire sleep coaches to ensure optimal sleep.

Sleep Timing

Everyone has their own circadian rhythms. Among other things, these control whether you feel sleepy or wide awake. To optimize your sleep, it is important to be in harmony with your circadian rhythm — in other words, if your rhythm is such that you want to be wide awake, you will not have much luck sleeping at that time. So, you want to time your sleep to coincide with your natural circadian rhythm. For most people, this means the ideal bedtime is somewhere between 8pm and 12am, unless you are a particularly strong lark or owl.

There is also the consistency of the timing of your sleep. In other words, if you want to optimize your sleep, you need to be going to bed and waking up at about the same time, seven days per week. The idea is to train your mind and body to expect sleep at certain times, and consistency helps to accomplish this. Of these, your wake-up time is the most important (because it is easier to make you wake up at a certain time, but it is tougher to force you to fall asleep). Some studies have found that sleep timing is even more important than duration or quality when it comes to mental performance.

So What?

There is a lot of well-intentioned information out there on sleep. But if you focus on any one particular factor such as the number of hours, you may be overlooking significant other factors that are known to contribute to optimal sleep. If you are serious about optimizing your sleep, you may want to take a close look at the quality and timing of your sleep as well as the number of hours.

Yes, it can seem like a lot of things to consider — this is a third of your life we’re talking about, after all! And if you want to optimize your daytime experience, optimizing your sleep is a non-negotiable part of that.