Why Do We Sleep? Get the Details, Here.

Why Do We Sleep? Get the Details, Here.

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Why do we sleep, when do we sleep, how do we sleep, and what happens when we're sleeping? Get the answers in the videos + text below.

Why do we sleep? Sleep is one of the most basic necessities of human functioning. We know sleep is critical for the body to balance and regulate its vital systems. But let’s look into the science behind sleeping — what happens when we’re asleep, and why we need to sleep.

Video: The Science of Sleep 

This video approaches the question, “Why do we sleep?” from a scientific perspective. It also suggests a practical sleep practices and applications informed by science. For instance, it discusses ideal sleep and napping patterns, why we sleep when we do, the symptoms of the most common sleep disorders, and current treatments available for those disorders.

Takeaways from The Science of Sleep

(Gleaned from McMaster University’s Demystifying Medicine Youtube video, above).  

How much sleep do we need?

Adults need 7 to 9 hours of sleep during every 24 hour period whereas adolescents need 10. It’s estimated that 23 percent of people get less than 6 hours of sleep a night, and therefore suffer from the effects of sleep deprivation.

How do we sleep?

Circadian rhythm

Many factors play a role in preparing your body to fall asleep and wake up. You have an internal body clock that has a 24 hour repeating rhythm called a circadian rhythm. Our circadian rhythm represents a big chunk of the answer to the question, “Why do we sleep?”

Two processes control our circadian rhythm. The first process involves our body and receiving cues from the environment such as light and darkness. The second process involves a rise in sleep inducing chemicals such as adenosine and melatonin, which slow down your breathing and relax your muscles.

When do we sleep?


Humans are a diurnal species, meaning we’re programmed to be active during the day and to sleep during the night. Chronotype is a term referring to the genetic and behavioral components affecting what time you go to sleep. Chronotypes can be separated many different ways, but perhaps the simplest is to divide them into two categories: early birds and night owls. Early birds prefer morning hours for intellectual or physical activity, whereas night owls sleep late and are more active in the evening.


And sometimes, we have those lovely little bites of sleep — naps. Taking a short middle-of-the-day nap now and again can be very good for you. What do naps do for us? Benefits of napping include improved: cognitive functioning, motor ability, productivity, and overall mood.

Types of naps 

Replacement naps — to compensate for a lack of sleep.

Prophylactic naps — in anticipation of a lack of sleep.

Recreational naps — sleeping just for fun.

why do we sleep
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When to nap

The best time to nap is between 1 pm and 4 pm. This is when the body naturally experiences a period of sleepiness — a dip in its circadian rhythm.

How long to nap

Power nap: A brief nap, as short as seven to 10 minutes is an ideal power nap. A nap this short in length results in an immediate reversal of sleepiness. Power naps improve productivity and their benefits can last up to three hours.

Medium nap: A 20 to 30 minute nap can result in some sleep inertia —  the disorientation that occurs directly after waking up. So the benefits of this slightly longer nap are delayed, but they are also longer lasting than those of a power nap.

Long nap: A two hour nap will result in extreme sleep inertia and an immediate decrease in productivity. But the potential benefits can last for up to 24 hours.

Sleep problems

Sleep disorders can interfere with a person’s physical, mental, social, and emotional functioning. If you think you might have a sleep disorder, take immediate action and see your health care professional.

3 most common sleep disorders

  1. Insomnia. This is the most common sleep disorder. It involves a difficulty falling asleep or staying asleep. Patients with insomnia wake up feeling groggy, fatigued, and anxious. There are over-the-counter drugs to treat chronic insomnia, and another good solution might be to try an all natural melatonin supplement, which can help regulate your sleep cycle.
  2. Parasomnias. These sleep disorders are also common and include phenomena such as sleep-walking and night terrors. Sleep walkers don’t usually remember much of what happened when they wake up. Night terror episodes can involve screaming, violent movements, and panic. The causes of most parasomnias are unknown.
  3. Sleep apnea. When breathing stops in irregular cycles or when muscles of the throat block the airway, causing snoring, this is sleep apnea. This sleep disorder is more common in adults, especially those who are obese or suffer from cardiovascular issues. Weight loss can be an effective way to reduce airway pressure and improve breathing. In more severe cases, surgery can be used to open the airway.

Good sleep habits

Proper sleep hygiene is vital to your health and wellbeing. One key aspect of good sleep health is to refrain from activities and substances that increase cognitive arousal late in the day. Another classic sleep hygiene rule is to avoid too long midday naps too often, and to develop a regular sleep schedule.

Video: Why Do We Sleep

Now we know quite a bit about the science of sleep — this thing we spend a whole third of our lives doing. Are you still curious as to more answers on why we sleep? Well, we don’t entirely know. But we do know sleep does a lot of things for us (some of which were outlined above!) If you’re still hungry for more sleep knowledge, check out this second video below for a closer look at how sleep works, why we’re not getting enough sleep, what happens if you DON’T sleep, and musings about where sleep came from in the first place.

We’ll let you form your own takeaways, on this one …

If you enjoyed either of these videos on the science of sleep and finding out the answer to the question of why do we sleep, share them! It’s vital and beneficial for us to be educated (and therefore empowered!) in regards to how our bodies and their processes work. When we know why and how we sleep, we can take accountability and responsibility for our sleep health. As a result, we will be healthier, happier people! So spread the sleep knowledge, and share the sleep love.

why do we sleep
photo: Envato Elements