Best Time to Sleep: Sleep Cycle Guide

Waking up groggy even after 8 hours? The problem may be sleep cycles, not hours.

What Are Sleep Cycles

Humans sleep in ~90-minute cycles: light sleep → deep sleep → REM (dreaming). Waking mid-cycle (deep sleep) causes grogginess; waking at cycle end (light sleep) leaves you refreshed.

The 90-Minute Rule

• 5 cycles = 7.5 hrs (recommended for adults)
• 6 cycles = 9 hrs
• 4 cycles = 6 hrs (minimum)

Example

Bed at 22:30 → wake at:

• 04:30 (6h) / 06:00 (7.5h) / 07:30 (9h)

Sleep Tips

• Same sleep/wake time daily (including weekends)
• No screens 30-60 min before bed (blue light)
• Dark, cool, quiet room
• No coffee after 2 pm

Calculate Your Sleep

Use our Sleep Cycle Calculator — enter bedtime or wake time for optimal times. Free.