Due to your tendency to stay up all night, whether you were praying to your god, or communing with nature, your circadian rhythm (or body-clock) has evolved drastically to the point where lack of sleep no longer taxes your body.
You no longer need to sleep, but can still be forced to sleep by magical means. To gain the benefits of a long rest, you can spend all 8 hours doing light activity, such as reading and keeping watch. Examples of "light activity" are at your DM's discretion, but the Player's Handbook describes light activity as eating, reading, talking, or keeping watch. As per ususal, an hour of walking, fighting, spell-casting, or similar activities interrupts your long rest and you must begin again.
Should you wish to sleep, each hour of sleep constitutes for two hours of light activity. For example, if you slept for two hours, you still must spend four hours doing light activity to constitute a complete long rest. For races that affect long rests, such as Elves with their Trance trait, or Warforged with their Sentry's Rest trait, then each hour in that semi-conscious state acts like an hour of sleep.
Your also learn two cantrips from any spell list, and the ability score for these cantrips is determined when you choose this feat. These do not count towards your cantrips known.
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