This is what I have begun to wonder about this interest in the old sleep pasterns. They&#x27;re usually put forward as healthier or the way we evolved to sleep. It seems to me it is more simply a symptom of going to sleep very early because the sun went down.<p>The sun is setting here at around 5:15 pm and rising at around 7:30. Twilight times are about half an hour more light around those times. If you&#x27;re going to sleep around 6pm because the sun has gone down, you&#x27;re probably not sleeping through until dawn which is 14 hours away. So you got up, did some stuff, it still wasn&#x27;t light out, so you just went back to bed.<p>It&#x27;s not because it&#x27;s healthier, or because you evolved to do so, it&#x27;s because your source of light hasn&#x27;t shown up yet. That changed with cheap electricity, because even candles weren&#x27;t quite as convenient or cheap.