Best Sleeping Bags for Staying Cool on a Warm Night

Q: What sleeping bag should I use if I don’t want the heat to get to me?
— Gus, Atlanta, Georgia

A: Many factors affect a sleeping bag’s comfort: rectangular or mummy design, temperature rating, down or synthetic insulation — it can be tough to find the right fit. Your easiest solution can be to simply unzip your sleeping bag when you get too hot. However, manufacturers are working on features so you can be snuggled up yet stay cool and comfortable. A few such sleeping bags I’ve checked out recently include:

• Klymit KSB 35 Sleeping Bag ($180, klymit.com)
• Zenbivy Bed 29º Synthetic ($209, zenbivy.com)
• Sea to Summit Ascent Down Sleeping Bag ($349, seatosummitusa.com)

The Klymit has a mummy hood with a draw cord to keep your head warm and can unzip from the bag’s top or bottom, providing airflow. There’s also a stash pocket inside the bag.

You can spread out with the Zenbivy. It’s actually multiple pieces: a top quilt with a fitted sheet and hood that wraps around an air mattress (mattress sold separately). Connect them with a series of clips to bundle up, or unhook them for a roomy night’s sleep.

The Ascent’s zippers can be configured so you can fold down the top third of the bag or unzip it completely. The bag also includes a foot vent to cool off on a warm night.