[noir_lord]

> I’ve always believed there was something to that.

Wouldn't surprise me, Humans don't have (by the standards of many mammals we share the surface with) particularly great night vision and prior to fire we'd have had no source of illumination but the moon/stars at night.

Basically stay in your cave/shelter til you can see whatever you are stalking/been stalked by.

[zokier]

The connection between available sunlight and human circadian rhythm is pretty well established, or more precisely how the lack of sunlight can lead to all sort of disorders, most obviously sleep and mood disorders.

More open question is how to counteract such negative effects. Supplementing daylight with high-power artificial light seems to be one of the most promising approaches. Simply sleeping more during shorter days is fairly speculative suggestion, at least as a "silver bullet".

That being said, simply based on personal experience I would expect that slight changes of sleep length could be possible. But the effect would be more like ±30mins to sleep length, when e.g. where I live currently daylight length varies from about 6 to 18 hours. Trying to match sleep to such a big swing seems pretty unlikely to succeed.