Most adults need 5-6 complete sleep cycles per night (7.5-9 hours). Each cycle lasts ~90 minutes and includes light, deep, and REM sleep stages.
You may be waking during deep sleep, have poor sleep quality, or need more/fewer cycles than average. Aim to wake at the end of a cycle, not during one.
Sleep inertia is the groggy, disoriented feeling upon waking, especially if awakened from deep sleep. It typically lasts 15-60 minutes but can be longer with sleep deprivation.
Waking during deep sleep (stages 3-4) causes more grogginess. Waking during light sleep or REM feels more refreshing. That's why cycle timing matters.
Maintain consistent sleep/wake times, keep the room cool and dark, avoid screens 1 hour before bed, limit caffeine after 2pm, and create a relaxing bedtime routine.
Yes. Adults need 7-9 hours, but teenagers need 8-10 hours, and older adults may need 7-8 hours. Sleep quality also tends to decrease with age.