Instead of sleeping your body enters a stasis for 4 hours a day. While in this stasis your body repairs any harm done. After resting this way you gain the same affects a person who's gotten 8 hours of sleep.

You have resistance to cold damage and climates.

You know the ray of frost cantrip. At 3rd level you cast the armor of agathys spell with this trait, without requiring a material component. Starting at 5th level you can also cast Rime's Binding Ice spell with this trait without using a meterial component. Once you cast Armor of Agathys or Rime's Binding Ice you can't cast those spells again until a long rest. Intelligence is  your spellcasting ability for these spells.