You can also download the Wim Hof app for free, which has a feature to guide you through the breathing exercise in a more personalized way.

If I said anything has a pronounced effect on sleep restfulness or concentration it's been whole plant based food which I tried incorporating in my diet more after watching Forks over Knives.

I still eat the occasional meat and cheese, but I found especially useful to replace dinner with WPBF. I naturally, i.e. without alarm, wake up after 6-7h of sleep instead of 9-10h, and I feel much more awake during the day.

I think it's mostly that if you eat heavy (greasy, meaty, cheesy) food in the evening your digestive system is so busy you can't sleep properly.

I would say the effect is much larger than cutting out alcohol, even though that's of course also helpful.