Why is there such a huge difference between sleeping 7.5 and 8.5 hours?

It’s truly astounding how an additional hour or even just an extra 30 minutes of sleep can drastically transform how I feel during the day. When I get only 7.5 hours of sleep, I feel like a total zombie, but with 8.5 hours, I feel energized enough to skip my morning coffee.

That last REM cycle can feel like finding gold for those who struggle with sleep. While the immediate difference is often in mood and perception, many of us can manage fairly well on about 70% of our usual sleep over prolonged periods.

@Dallas
Really? I always thought that only applies to a single night of poor sleep. If you generally sleep well but then cut back one night, you might be fine. But if it happens repeatedly, it’s going to take a toll.

@Noah
Without REM sleep, you’re double doomed.

@Dallas
In your example, if 8 hours is ideal, then 5.6 hours is 70%. I don’t think anyone can function well on that little sleep every night or even for several nights in a row.

@Westley
They tend to be somewhat accurate but are more reliable for comparing your own sleep patterns over time rather than providing precise measurements.

I think the key might be what sleep stage you wake up from. Getting jolted awake from REM sleep feels terrible and disorienting, but waking from light sleep seems to allow for a more refreshed start.

Oak said:
I think the key might be what sleep stage you wake up from. Getting jolted awake from REM sleep feels terrible and disorienting, but waking from light sleep seems to allow for a more refreshed start.

That sounds right, but I think the grogginess only lasts for a short while after waking. It shouldn’t ruin your entire day. Maybe it feels bad for an hour or until the REM cycle would have naturally ended.

Linden said:
Feeling like a zombie after 7.5 hours? That’s actually quite a bit of sleep for many people.

For those dealing with insomnia, hitting that last REM cycle makes a world of difference, explaining the drastic change with just an extra hour.

Feeling like a zombie after 7.5 hours? That’s actually quite a bit of sleep for many people.

@Blair
But if you’re managing 7.5 hours regularly, doesn’t that mean you’re not really experiencing insomnia? And if it’s less because of actual insomnia, then any decent sleep feels great, right?

@Blair
How many REM cycles should one have each night? My smartwatch shows only 2 cycles totaling 55 minutes.

Westley said:
@Blair
How many REM cycles should one have each night? My smartwatch shows only 2 cycles totaling 55 minutes.

What app do you use to track that?

Cameron said:

Westley said:
@Blair
How many REM cycles should one have each night? My smartwatch shows only 2 cycles totaling 55 minutes.

What app do you use to track that?

It’s a sleep app that divides sleep into REM, deep, and light stages. Not sure how precise it is.

Westley said:
@Blair
How many REM cycles should one have each night? My smartwatch shows only 2 cycles totaling 55 minutes.

Two cycles with only 55 minutes of REM doesn’t sound right. A full cycle is about 90 minutes, and you should be having 4-5 cycles per night.

Linden said:
Feeling like a zombie after 7.5 hours? That’s actually quite a bit of sleep for many people.

I usually sleep between 5 and 7 hours a night and that feels sufficient.

Linden said:
Feeling like a zombie after 7.5 hours? That’s actually quite a bit of sleep for many people.

Sleep needs vary significantly among people, typically ranging from 6 to 8 hours, though it seems you might need a bit more.

Linden said:
Feeling like a zombie after 7.5 hours? That’s actually quite a bit of sleep for many people.

I’m happy if I can get 6.5 hours on a good night.

Hollis said:

Linden said:
Feeling like a zombie after 7.5 hours? That’s actually quite a bit of sleep for many people.

I’m happy if I can get 6.5 hours on a good night.

My work schedule hardly allows for more than 5 hours of sleep.

Linden said:
Feeling like a zombie after 7.5 hours? That’s actually quite a bit of sleep for many people.

If I could get even 6 hours, I’d be over the moon.