Okay, I’m curious to find out once and for all: Is there any significant difference to the average adult human body physically or psychologically between the following two scenarios:
Exactitude to the scenarios isn’t important to me; the general question is.
I’ve got multiple conflicting instincts on this, especially when I read that sleep divided into two periods used to be common in the very old days (I forget when).
I’m no scientist, but isn’t the importance to get complete sleep cycles?
Ideally, your night sleep will end without you requiring an alarm. So you end up getting as much as you need - for me, it’s right about 8 hours (which wound be six 80 minute cycles)
I’d think naps are similar. What’s “ideal” doesn’t require you to establish any artificial time constraints. You’ll sleep as long as needed. For me, it ends up being just under 55 minutes from when I lay down to when I awake (on weekends, when I have the time)
Sorry, does the link demonstrate that there is a significant difference, and sleeping through the night is superior? Just want to make sure I understand.
I’ve helped to crew a relatively small ocean going vehicle on multi-day journeys.
The schedule was 3 hours of taking watch, 3 hours of free time, and 3 hours of sleep.
8 hours of sleep is 1/3rd of your time on a 24 hour schedule so, functionally, there shouldn’t be any difference. But, let’s suffice it to say that it’s miserable to do.
Right, I do get that, say, sleeping according to the rhythm of a newborn isn’t ideal, even if it’s eight hours total. But I was wondering more along the lines of a more reasonable single nap, maybe also at what point it DOES matter.
I’ve also hiked and, in general, without artificial light and insulation/temperature control it’s very easy to adapt to a sunset/sunrise schedule.
I’d generally assume that biphasic sleep, in history, was at least somewhat seasonal. During longer nights, you’d probably get more sleep than you need so you’d probably start waking up in the middle of the night.
In the summer, in hotter regions, you might have a midday siesta. Again, my guess would be that this largely occurs naturally. In the heat, your body basically tells you to go find some shade and take a break. But, these are people who are out working the fields, chasing down animals, etc. not sitting at a computer.
But in equatorial, tropical, and Arctic regions, that might not have been the case. Those are just things we know from the more populated regions in Western history.
My sense from my experience is that your body knows what it needs in nature.
In modern life, I’ve napped and had it be good and I’ve napped and had it throw off my schedule and ruin several days.
My current best bet would be that napping, minus physical effort like heavy lifting or long hikes up mountains, is generally unwise if you have gotten enough sleep, otherwise.
I think the details do kind of matter here.
These are all different:
Your body needs a certain amount of time to get through a sleep cycle, and you need several of them per day. The extreme example of eight separate hour-long naps wouldn’t work. Blocks approaching 4 hours might, but ideally 6+ would be better.
Even if you could time the cycles perfectly to squeeze each one into a perfect 2 hour block every time, I think there would still be some other bodily systems (outside just the brain) that wouldn’t respond well to such short rest cycles.
Don’t know anything beyond that simplistic answer…
I think my main interest would be in the first two, maybe three. After that, like I said, I know enough about new parents that I can guess that it’s not ideal.
I, too, would be interested in any expert opinions on this subject. My only contribution here is anecdotal.
The traditional view is that a continuous ~8 hour block of sleep is important because of the sleep cycles we go through, and specifically the period of deep REM sleep (“Rapid Eye Movement”) where we dream. For most of us, though, as you get older, sleep becomes more intermittent.
I’m old enough to be in that category. I tend to wake up many times during the night, and will sometimes watch a movie in bed, and then go back to sleep, which typically lasts only a few hours or less. But, going back to the REM sleep theory, what I find is that I often have dreams during these short sleep cycles, so whatever purpose is being served by the “deep sleep” phase appears to occur naturally even during these short cycles.
Biphasic sleep is getting a bit of attention currently. Either a broken night, with waking for activity in the early hours, or nighttime and siesta. Both seem to work. Our modern regimented life seems to work against such patterns in unhelpful ways.
I have always tried to get roughly 90 minute cycles if I’m having trouble with sleep. For me that seems to provide a refreshing totality of sleep. Shorter periods don’t work. Anything where you are forcibly awoken mid cycle seems to essentially nullify the value of the cycle.
The various depths/modes of sleep all need to be present, as each has its role in body and mind maintenance. Punctuated sleep can and will wreck this.
YMMV.
Interesting topic for me. Especially today.
My Wife and I have always been very early risers. Now it’s about 4am.
This morning I woke at 1:30 am and could not get back to sleep. Somethimes iit helps to go to the couch. I call it a change of venue.
Well that didn’t really work. By 3am I gave up and got on the SDMB. I suspect I will ‘nap’ latter in the day, but frankley, that really throws me off and I feel real weird when I get up after a nap.
A sleep cycle is about 90 minutes. So blocks of time that don’t allow you to get in full sleep cycles are less useful.
I’ve read a bunch of articles recently associating napping with an increased risk of dementia. But i suspect the causation goes the other way, that is, i think aging brains may ask for more sleep. I don’t think anyone has done a study that would distinguish why there’s an association.
I do not have any scientific evidence, but I know for me that on days when I only get 6 hours of sleep, then take a 2 hour nap in the afternoon I feel better than when I sleep 8 hours straight.
I don’t know how long we have to go in factual questions, but I’m seeing multiple personal anecdotal data points, so I will give my own. I can’t remember the last time I got even close to 8 hours of actual sleep over 24 hours (sounds dreamy). I do know that on the nights that I get way too little sleep (4-5 hours’ish) and then try to catch up with a 1 hour nap, it doesn’t work. I would much prefer to get the normal 6-7 hours of intermittent sleep overnight. I wish I could nap - doesn’t work for me.
How long after shutting your eyes does a sleep cycle start?
I don’t know in general, but i assume it varies. Certainly, it varies just for me.
FWIW.
https://www.sciencedirect.com/science/article/abs/pii/S108707922400093
Overall, habitual napping increased the risk of several adverse health outcomes, including all-cause mortality, cardiovascular disease, metabolic disease, and cancer, and decreased the risk of cognitive impairment and sarcopenia. Individuals with a napping duration of 30 min or longer exhibited a higher risk of all-cause mortality, cardiovascular disease, and metabolic disease, whereas those with napping durations less than 30 min had no significant risks. No significant differences in napping and health risks were observed for napping frequency, percentage of nappers, sample size, sex, age, body mass index, follow-up years, or comorbidity status
Huge meta analysis and not related to comorbidities but still association not necessarily causation.
As to why?
frequent napping has also been associated with numerous negative outcomes (eg, cognitive decline, hypertension, diabetes), particularly in older populations. This association exists even when statistically controlling for relevant health- and sleep-affecting determinants. An emerging hypothesis suggests inflammation is a mediator between mid-day naps and poor health outcomes, yet further research is necessary.
Functionally in adults they ARE different, less REM:
In infants, naps are indistinguishable from nocturnal sleep, as both are REM-rich [1] (Figure 1). Later during early childhood, naps are predominantly composed of NREM sleep with very little REM [31]. Young adult naps, if of substantial length, will contain both NREM and REM bouts [32]. Naps of older adults are dominated by lighter NREM stages, a short bout of SWS, and less often, REM sleep [10].
And naps have the potential to disrupt the sleep architecture of nocturnal sleep:
At times, naps reduce sleep pressure so thoroughly that subsequent nocturnal sleep can be disturbed
And @puzzlegal you are in agreement with the consensus on causality direction for cognitive decline:
The link between cognitive decline and essential napping has been viewed predominantly with the opposite causal directionality as the link between mortality and napping. That is, rather than naps being a detrimental factor, they are predicted to be a byproduct of related factors. For instance, it has been posited that age-related changes in brain integrity lead to sleepiness, which then induces napping. Brain damage and neurofibrillary tangle deposition brought about by early cognitive decline, particularly in the brainstem [96], alter cholinergic activity that is necessary for proper sleep/wake maintenance [97].
Lots to ponder in the article but bottom line is that napping may be a mixed bag. The FQ response though is that there are significant functional differences between napping and nocturnal sleep, beyond enough time to get full sleep cycles in.
I wasn’t able to see your link, but got to it here:
To nap or not? Evidence from a meta-analysis of cohort studies of habitual daytime napping and health outcomes - ScienceDirect)
I have real concerns about a metastudy that infers causality without a longitudinal analysis that evaluates health before and after a course of napping (I understand you said ‘FWIW’, I’m just following up on that). It’s highly plausible that people with chronic health issues (apnea, depression, etc.) nap more.
Precisely!
Right for instance:
I know that i am more inclined to take a nap when i have troublesome inflammation (from disease, injury, whatever) than when i don’t.
Yes and the second article is very aware of these items:
Given the unexpected nature of these associations, examining directionality between napping and poor health is critical. Here, we will specifically focus on the link between napping and both mortality and cognitive decline.
3.1.1 Essential napping and mortality
Prospective investigation of causality (ie, random experimental group assignment) between frequent napping and mortality is not feasible, yet there are several studies that have attempted to disentangle this relationship …
The morning waking period corresponds with an increase in blood pressure, heart rate, and platelet aggregability [90], potentially due to reactivation of the sympathetic nervous system that occurs upon awakening [91]. In response to this rise, both vascular sheer stress and myocardial oxygen demand increase [66], and incidence of cardiovascular events rises. It is proposed, then, that the afternoon nap provides a second waking opportunity and thus a second opportunity for cardiovascular events to occur [87].
Supporting this hypothesis, individuals who frequently nap but also have a history of myocardial infarction (heart attack) do not have an increased risk of mortality [87]. It has been suggested that these individuals, who are likely regularly taking beta-blockers or aspirin (which both provide favorable cardiac benefits), may be unknowingly decreasing their risk of nap-induced cardiac issues [93]. Additionally, as blood pressure and heart rate decrease linearly with longer sleep periods [94], it is plausible that longer periods of sleep trigger larger increases in blood pressure/heart rate upon awakening. This hypothesis would explain why longer naps seem to be particularly dangerous [5,27,85].
Including inflammation directionality -
3.2.1 Sleep and inflammation: a bi-directional relationship
Sleep impacts the immune system [114], potentially via the glymphatic system [115]. Consequently, individuals with disturbed sleep, such as those with insomnia and untreated sleep apnea, tend to have immune alterations and chronic inflammation, a non-specific immune response [116]. On the other hand, the immune system modulates sleep. Through two separate immune cascades, inflammation causes daytime sleepiness [112]. Within one pathway, IL-1α elevates body temperature to prepare for immune recovery [117]; elevating temperature is metabolically costly. Given that energy expenditure is low during NREM sleep relative to wake and REM [118], having a large portion of NREM is advantageous for immune-induced recovery. Therefore, sleep occurs in response to this metabolism/temperature increase as a means of energy preservation [112]. Notably, daytime naps–especially in older adults–are NREM rich [10] (Figure 1), and thus they may be optimal for responding to such increased energy demands.
Their bottom line is that dysregulated inflammation mostly causes both increased napping and negative health outcomes:
This suggests that napping itself is not detrimental and that inflammation may precede both napping and poor health outcomes; however, prospective investigation is required to confirm this hypothesis.