We’re often told to aim for 8 hours of sleep, but sleep science shows that it’s not just about quantity — it's about timing.
Our sleep happens in cycles, typically lasting around 90 minutes. Each cycle includes different stages of sleep, from light dozing to deep restorative rest and REM sleep. Interrupting a cycle can leave you groggy and disoriented, even if you've had a full night’s rest.
That’s why waking up in the middle of a sleep cycle can feel worse than getting less total sleep. It's not about the hours — it's about the rhythm.
Try using our Sleep Time Planner to calculate your ideal bedtime based on your wake-up time.