I used the '90 minute sleep rule' to stop morning grogginess — and it's better than any alarm clock

Focusing less on total sleep duration and more on timing your alarm so you wake-up on the cusp of a sleep cycle, this rule ...
Los Angeles Times

Tired All the Time? Your Sleep Cycles (Or Sleep Calculator) Could Be the Key to More Energy

Ever wonder why some mornings you wake up ready to go, and others you feel like a zombie? The difference often comes down to when you wake up during your sleep cycle, and that’s exactly what a sleep ...
Hosted on MSN

My Apple Watch says I'm getting 90 minutes of deep sleep — is that enough?

I check my Apple Watch every morning to help me understand my sleep and one metric always stands out as worryingly low. Despite regularly clocking up over eight hours of happy snoozing, deep sleep ...