How much sleep do you actually need? What time should you go to bed? What time should you wake up? How does changing your rhythm affect your health and physique?
There is this charming notion that if we look back from our great grandparents all the way to our Palaeolithic ancestors, they would have rested their heads with the sun setting in the evening and slept restfully throughout the night until dawn, a solid 8-10 hours. Well, they certainly didn’t have laptops, cellphones, tablets and external light sources keeping them up, so this must clearly have contributed to their strong and fit bodies that were free of chronic disease.
A recent study on modern day hunter-gatherer tribes found they sleep an average of 5.7-7.1 hours per night. This is pretty much on par with the North American and European average of 6.5 hours. While there is no doubt that sleep duration/quantity affects overall health, performance and BMI, what this tells us is that sleep may have more to do with "sleep patterns" than overall sleep duration.
Sleep longer in the winter
Several studies have shown that the later your go to bed, the greater your risk of weight gain. If you sleep less than 5 hours, your chances of catching a cold or flue increase by 450%! The average bedtime for tribes in the winter is 9:15pm vs. 10:45pm in the summer.
The take way: Adjust your sleep patterns with the seasons and use the sun as your guide.
Wake up with morning light
We have all felt it at some point – dragging yourself out of bed in the morning feeling exhausted. The tribal groups studied woke up with the morning sun throughout the entire year. They perform the majority of their work in the morning before the midday heat, exposing them to lots of natural light.
Take away: Use light to wake up and expose yourself to it all morning long.
Here is an excellent called a “wake-up light alarm clock”.
To sum it up, your duration should be similar to the pattern of the sun. Sleeping in isn’t the same as going to bed early. Favour going to bed early in the winter to catch up on sleep and use a wake-up light alarm in the morning.