Why do we feel so tired all the time? Head squeeze’s Hannah Fry looks at the reasons modern life might be exhausting us, from irregular bedtimes to blue lights from our phones.

While you are thinking about tiredness, here are some more sleep-related questions to ponder:

Why exactly do we yawn?

Could you train yourself to function on less sleep?

Is it true that people are either larks or owls?

What do animals dream about?

When we dream, does time pass faster or slower?

… and why don’t we say goodbye to winter tiredness altogether and hibernate like other animals?

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