I´ve heard a lot of people talking about having an LD in a nap.
my question is, are you always in REM if you take a short nap during the daytime, or do you have to nap for a certain amount of time (90-120 minutes for example), or is it random if you are going to have a REM period.
You might hit REM if you're very REM-deprived already, but otherwise I think it's more likely to be non-REM sleep unless it lasts quite a while. But it could depend entirely on the person.
Personally, the only time I normally feel like napping is when I've not had enough sleep the previous night. But even in those cases it doesn't seem to last more than an hour, and I rarely seem to encounter any actual REM or dreams, unless I had been severely lacking in nightly sleep.
I think it depends on what phase of sleep you need. From what I understand, the brain prioritizes the type of sleep that it needs most, first. For most people in the Western world, we skimp out on the last hour or two of sleep, which is the most REM heavy. This means, if you sleep 6-7 hours and get up, when you take a nap you're most likely to rebound on that REM sleep you missed. Missing that last hour or two of sleep is actually devastating for our sleep and, as a result, our health. When daylight savings time shortens our sleep by an hour, there's an uptick in heart attacks on that day, while the opposite is true when we gain the extra hour of sleep. Regardless, if for whatever reason you happened to have less deep NREM sleep the night before, your nap would put you into that area of sleep that was lacking first. Though, it's important to remember that dreams do not exclusively happen in REM sleep, they just happen there more reliably. Dreams have been recorded in NREM sleep in the lab before, so it's possible you could have a dream during your NREM nap, but it may not be as robust or ripe for lucidity as normal REM dreams are.
When I was very sleepdeprived, because of babys, it was the only time when I had intense WILDS. It was in morning naps, directly, not after sleeping, with music on for concentration. There always was a moment of forgetting between the wild experience and being aware, but it was at the beginning of the nap.
The nap was hours after waking up early morning, but still in the morning hours. I remember one in afternoon, but it was definately because of the sleeping pattern that was completely upside down during the night. It's an advantage of the deprivation. Napping is worth trying if you've to catch up sleep at any moment I think, but I had more luck in the morning hours. I would not make it a goal in itself, if you're already rested enough you risk the problem of not falling asleep in the evening. If I sleep during the day falling asleep in the evening is more difficult and might influence REM I guess.