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What’s the science behind good sleep? How much sleep do we need and how can we become sleep experts in our own homes? This article will dive into the findings of a recent sleep study  But first, why the interest? 

I’ve just spent a few days in the Cape Town winter. It’s a huge contrast to Durban’s warm, sunny and light winter months. What I noticed most was how my body responded to it. In Durban, I naturally get up at around 05.20, at dawn. By 06.30 I’m on the promenade either running, walking or swimming. I easily wake up and am energized and refreshed. 

It feels like my body wants to sleep more, even though I’ve already gotten my usual 8 hours

Contrast this with Cape Town wintery August. Sunrise is 07.30, not, 06:10 like Durban. In Cape Town, my body naturally wakes up a whole hour later. The room is cold. I’m warm under my covers and I find it difficult to get myself going. It feels like my body wants to sleep more, even though I’ve already gotten my usual 8 hours. 

The science behind this is getting clearer. In 2017, the Nobel Prize for Medicine was awarded for research on circadian rhythms. It was found that internal clocks and biological rhythms govern human life. This article will unpack this natural phenomenon. 

The Important Determinants of Sleep

In a recent UCLA sleep study, three geographically different hunter- gatherer tribes were analysed. The sleep, movement and exposure to light were all documented through a wrist monitor. Through this, we now know that timing and duration of sleep are key to our quality of sleep. They’re also independent from one another. Duration is the amount of sleep you get over a 24-hour period. Timing is when that sleep occurs within that period. Both of these factors are influenced by natural light, ambient temperature and seasonal changes. 

What did the study  find? There’s a common misconception that it’s natural for us to wake up with the sun and go to sleep with the sun. Actually, it’s common for hunter-gatherer tribes to tell stories around a fireplace or dance until late at night. It’s found that these tribes, on average, go to sleep around 3.5 hours after sunset. It’s noteworthy that they don’t use technology, especially after dark. These unnatural light sources impact on our natural circadian rhythms. 

When our circadian rhythms wake us up naturally around dawn. This is when our bodies warm up. The warmth stimulates alertness.

So, if you’re going to stay up past sunset, go dance around a fire! What’s also interesting, is that these groups also didn’t wake up at sunrise. They woke up before it. Not because of the dawn light, but actually because of their body temperature. Body temperature correlated the most strongly with the time that they would fall asleep and the time they’d wake up. When temperature drops at night, energy usage drops in humans, which initiates falling asleep. 

Related to this, getting into a hot bath before bed will help your body to cool down. It causes your blood vessels to dilate to allow your core temperature to decrease. Your body is trying to get rid of excess heat. You step out of a hot bath, you’re still losing heat. Your body temperature drops and your start to feel sleepy. 

Likewise, when the temperature rises in the morning, before sunrise, our bodies get a little bit warmer. This warmth stimulates alertness and wakes us up. 

How Much Sleep Do You Need? 

The sleep study found that the hunter gatherer groups only spent about 5.7 – 7.1 hours sleeping  per night. This is contrary to what we’ve all been hearing, right? The normal recommendation is 7-9 hours of sleep. What’s important to note, is that it’s different for everyone. Also, there’s a winding down sleep period that’s longer than your sleep duration. Your sleep duration period, may be 7-9 hours, where you’re getting ready for sleep, reading a book, etc. The sleep time is when you’re actually sleeping. 

If you’re trying to reach your cognitive, memory and information processing potential, you might actually need more sleep. The best way to test that is to make a note of how well you think you’re performing, how alert you are and how sharp you feel the next day. If you feel that you aren’t on top of things, or you’re constantly grabbing a coffee, then maybe you need more sleep. In this case, experiment with going to sleep earlier and waking up naturally, within a 7-9 hour sleep period. 

5 Sleep Hacks for a Good Night’s Sleep

  1. Sleep in a cool room
  2. Have a warm bath before you sleep
  3. Get bright light exposure during the day. If you do this, you’ll be less sensitive to light at night
  4. Exercise outside if you can
  5. Don’t make wearing sunglasses your default. Spend time outside without sunglasses

Now that you know the science to good sleep, enjoy that hot bath this evening and listen to your body when it wakes you up before sunrise. If you’d like to know more about how to optimize your sleep, take a look at this post. It’s called Seven Steps for Significant Sleep, and dives into easy ways you can improve your sleep.