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Why do some people feel sluggish/groggy when they slept 7 hours the night before?
Why do we feel well-rested after a nap? Is it because you’re getting sleep during the PM hours?
Or why is it that when you go to bed early, you not only wake up early but have loads of energy before the sun rises?
These are just some of the questions that pop in my mind and today you’re gonna have the answers to them.
THE HOURS BEFORE MIDNIGHT
This used to be my hypothesis…
A while back I heard that, as far as sleep goes, every hour of sleep you get in the PM, those hours count as two hours. Or your body “thinks” it got two hours of sleep.
Example being…You fall fast asleep at 10:00PM and wake up at 5:00AM.
On paper, you got 7 hours. But your body “thinks” it got 9 hours because hours 10PM-12PM doubled.
Hopefully that makes sense.
There’s also an age-old expression our grandparents would say in regard to sleep…
“It’s the hours before midnight that count”.
As it turns out, my theory of “tricking” your body into “thinking” it got more sleep than in reality has no science supporting it.
But our grandparent's wisdom does have some merit behind it.
And it’s a blend of science and old wisdom.
The idea that “sleep before midnight is more important” comes from both circadian biology and anecdotal experience. What’s really going on ultimately boils down to two things…
Your Circadian Rhythm
When deep sleep starts
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Here’s are the facts…
1. Your body follows a circadian rhythm
Your internal clock (circadian rhythm) is regulated by light and darkness. Around 9–10 PM, your body starts releasing melatonin, making you sleepy.
By midnight, you’re usually entering the deepest, most restorative stages of sleep — if you’re already asleep by then.
2. Deep sleep happens earlier in the night
The first half of your sleep (between 10 PM and 2 AM) includes more deep sleep (slow-wave sleep), which is:
• Crucial for physical recovery
• Supports the immune system
• Helps with muscle growth and hormonal balance (like growth hormone)
The second half of your sleep (closer to morning) includes more REM sleep, which supports memory, mood, and mental recovery.
So, if you stay up late and only sleep from 2 AM to 9 AM, you’ll still get 7 hours — but you may get less deep sleep, which makes you feel less restored.
Summary in One Sentence:
Going to bed earlier (e.g., 9–10 PM) may help you get more of the deepest, most restorative sleep, especially if you wake up early.
People who go to bed earlier often sync better with their circadian rhythm, leading to deeper, higher-quality sleep. Anecdotally, they feel more refreshed even with fewer hours.
Shift workers or night owls often report worse sleep, even if the duration is the same. That’s because it’s out of sync with natural light-dark cycles.
So going to bed earlier (e.g., 9–10 PM) may help you get more of the deepest, most restorative sleep, especially if you wake up early.
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