DJ__Hanzel t1_iuiwgbg wrote on October 31, 2022 at 5:50 PM

Difficult ELI5.

We don't know anywhere nearly enough about REM sleep as it is. Nor the brain very well as it is. They all would impact REM in different ways.

Sleep works kind of like this:

NR1 Sleep (non-REM 1) - Very light sleep. You will feel like you just nodded off. When you awake from it, it doesn't even feel as though you slept. Very low demand sleep. This is what you aim for in a quick nap - under 15 minutes.

NR2 Sleep (non-REM 2) - Lighter sleep that comprises most of your time slept. Feels like more than nodding off, but still not too deep in sleep to be awakened. Good for long naps - under 45 mins.

NR3 sleep (non-REM 3; also known as Delta Sleep) - Deep sleep. Difficult to be awakened at this time. Most restful portion of sleep. This is when the body and brain repair themselves.

REM sleep (Rapid Eye Movement Sleep) - This is when you dream. It is the most demanding part of sleep. Your heart rate increases and becomes variable. Your brain activity flies through the roof. This part of sleep is believed to be responsible in processing emotions and cementing memories.

*My weird little opinion on REM sleep, which is by know means factual: We need to experience things to learn. Our dreams are our way of simulating these things into a way we can experience them, process them, and cement them. Again, by no means factual.

After REM it circles back and continues in layers: NR3, NR2, NR1, repeat. (NR1, NR2, NR3, REM, NR3, NR2, NR1, NR2, etc.)

A common REM suppressor, cannabis, impacts REM cycles by shortening them. With shortened REM cycles, though, comes with more non-REM sleep (NR1/2/3) in a similiar period to someone with regular length REM cycles.

So a person who uses cannabis and sleeps the same amount of time as somebody who doesn't use cannabis would theoretically get a more restful sleep than the latter, based on cannabis' impact on REM sleep, alone (not taking into account physiological effects). But the cannabis user would have gotten less REM sleep and time to cement their memories.

Bobithie t1_iujo2f7 wrote on October 31, 2022 at 8:55 PM

Anyone else take a 15 minute nap, have dreams (so presumably experience REM sleep) and wake up feeling crazy rested?

vokzhen t1_iujwo4q wrote on October 31, 2022 at 9:58 PM

We used to believe dreaming always happened in REM sleep, but we've later discovered that's not actually true. It can happen in the other stages as well, most often in NR3 and least often in NR1.

But it's also possible it was "hypnogogic hallucinations," which can be a dream-like state as you're falling asleep. If you've had the experience of thinking about something and suddenly jerking awake (hypnogogic jerks) and feeling like you were in a light dream, it was probably that an not a "true" dream (if the two can even be fully distinguished, I'm not up to date on the research). For me, whether by jerking awake, or rolling over, or something else, I often "wake up" from a hypnogogic hallucination and find myself feeling well-rested, regardless of how tired I was just a few minutes previous.

MrLongJeans t1_iujox4e wrote on October 31, 2022 at 9:01 PM

I had three separate nightmares, like different setting and circumstances and narratives, in like 30 minutes last night (I noticed what time I went to sleep and what time I awakened). So, yes?

SoManySNs t1_iujp4ct wrote on October 31, 2022 at 9:03 PM

To address OP's specific question about SSRIs: One of the objective findings in people with depression is decreased REM latency (so you fall into REM faster), and increased total REM sleep. There can, of course, be other sleep disturbances such as insomnia or hypersomnia. But, all things being equal, a depressed person will spend more time in REM and less time in Stages 1-3.

All that is to say, decreased REM sleep from SSRI use may actually be normalizing your sleep cycles, rather than "disrupting" them. I'm not familiar enough with the literature to say that for certain, though.