How's this for an answer: some likely did, but others likely didn't.
One caveat: I'm coming at this from a slightly different angle, which is familiarity with the history of sleep research rather than that of the eras you're asking about - so it's one reason I'm hopeful some of the medievalists and early modernists here chime in as I'm quite curious what (if any) debate there's been on this in their fields.
That said, the main contributor to noctural biphasic theory (versus biphasic in general, which can refer to daytime siestas as well) is a historian at Virginia Tech by the name of Roger Ekrich, who back in 2004 wrote a survey of nocturnal habits throughout the world, At Day's Close - Night in Times Past. While much of the book dealt with various societal oddities throughout Europe at night, the one that caught the most traction was his analysis of literature that suggested that pre-industrial age humans slept somewhat differently than we do today:
Until the close of the early modern era, Western Europeans on most evenings experienced two major intervals of sleep bridged by up to an hour or more of quiet wakefulness. In the absence of fuller descriptions, fragments in several languages in sources ranging from depositions and diaries to imaginative literature give clues to the essential features of this puzzling pattern of repose. The initial interval of slumber was usually referred to as “first sleep,” or, less often, “first nap” or “dead sleep.” In French, the term was premier sommeil or premier somme, in Italian, primo sonno or primo sono, and in Latin, primo somno or concubia nocte. The succeeding interval of sleep was called “second” or “morning” sleep, whereas the intervening period of wakefulness bore no name, other than the generic term “watch” or “watching.” Alternatively, two texts refer to the time of of “first waking.”
Both phases of sleep lasted roughly the same length of time, with individuals waking sometime after midnight before returning to rest. Not everyone, of course, slept according to the same timetable. The later at night that persons went to bed, the later they stirred after their initial sleep; or, if they retired past midnight, they might not awaken at all until dawn. Thus in “The Squire’s Tale” in The Canterbury Tales, Canacee slept “soon after evening fell” and subsequently awakened in the early morning following “her first sleep”; in turn, her companions, staying up much later, “lay asleep till it was fully prime” (daylight). William Baldwin’s satire Beware the Cat recounts a quarrel between the protagonist, “newly come unto bed,” and two roommates who “had already slept” their “first sleep.”
Men and women referred to both intervals as if the prospect of awakening in the middle of the night was common knowledge that required no elaboration....
Ekrich goes on to review a reasonable amount of contemporary literature that suggested this was fairly commonplace and to note a series of early 1990 experiments by Thomas Wehr at the NIH that artificial light appeared to be one of the primary culprits responsible for disturbing biphasic sleep, along with a walk through what people actually used to do in the middle of the night.
So far, so good, and Ekrich continued this research across cultures and published in several fairly well respected journals, lectured in front of medical faculties, and even is on the board of the main publication of the National Sleep Foundation.
Except then in the early 2010s, his theory took a bit of a hit. Several anthropologists got interested in the subject, and realized that their field provided a fantastic opportunity to check on this with current day isolated preindustrial societies. The result was a 2015 paper, Natural sleep and its seasonal variations in three societies, that went a step further and put Actiwatches on current day pre-industrial societies near the equator - and noted precisely none of them experienced biphasic sleep.
Ekrich's response is quite interesting, and in a sign of the importance his theories had gained it appeared in what's considered the main sleep research journal, Sleep. But the relevant part for your question is this portion:
As I have recently written at length, consolidated sleep to which the industrialized world aspires, if not always successfully—due perhaps to the persistence of this once dominant pattern—is for Western societies a remarkably youthful form of sleep, a product not of the primeval past but of forces grounded in technology (artificial illumination) and shifting cultural attitudes toward sleep over the course of the Industrial Revolution. This is not to argue that segmented sleep has been the predominant pattern of sleep among all preindustrial peoples in the non-Western world. [emphasis added]
So, the best answer is probably that it depends on the population and possibly where they're located, along with how much artificial light they were exposed to.
Edit: And thanks for the gold, kind stranger!
This post has an answer by /u/hillsonghoods that discusses what you’re asking about.
I'm glad you didn't specify any particular place or time because I'd like to add some info about Africa here. I haven't studied sleep specifically, but you do run into it in anthropology. Particularly, there is a remarkable study 1 by Hewlett & Hewlett comparing the sexual habits of two neighboring communities of Aka foragers and Ngandu (Bantu speaking) farmers in central Africa. This paper could only be done because the two researchers had known these communities for 20+ years, only then were they able to pry at some fascinating questions about touchy subjects, ones which most people wouldn't tell a random inquisitive outsider. Some of these responses might be quite shocking to our delicate sensibilities...Both societies observed a "post-partum taboo" which meant that for a year after birth the couple shouldn't have sex. For the Ngandu men and women interviewed, 100% believed in the taboo and a staggering 90% of the men said they simply left the household to go to another town to have sex with other women during this time! One man said:
No way I will wait one year. I will search for another woman, masturbation is not an option. If I search far away I will use a condom. I am not searching for children, only pleasure.
Even though this is "accepted behavior" it is still not good. If you do this, your child could catch ekila dibongo (taboo disease of the knees) which can be fatal. So to safeguard their philandering, men then use medicines (on themselves) to fight the disease. I'm in the United States, and I don't think I could possibly convince my wife to agree to this situation for the first year of our baby's life. In fact, if I said this in all seriousness, I'd probably get an angry response or even slapped; a reminder of how different social worlds can be sometimes.
But you're asking about sleep patterns...So both Aka and Ngandu people woke up multiple times during the night for a bit, to do things like have sex, maintain the fire, take care of an infant, to talk, or to eat. And to be clear, people weren't having sex every night, but would have a session for one night and then rest for a few nights. This averaged 2.1 days of resting for Aka couples and 2.7 days of resting for Ngandu couples. On average, Aka couples aged 18-45 had sex 3 times a week and 3 times a night each session. For Ngandu couples aged 18-45, it was 2 times a week and 2 times each session. Each "time" was sex until male orgasm, as men reported (Aka men formally and Ngandu men informally) that they had an orgasm each time. But for women, both groups said they had an orgasm "at some point" or only once the whole night (though some had more).
This was the average, so sometimes it was 5 times a night. As one Aka man said, "...If I do not do it five times my wife will not be happy, because she wants children quickly." Also, some Aka men have second wives, although this socio-sexual triangulation (and how it relates to their sleeping patterns) was not questioned by the researchers. An Aka man said, "My father is dead and I need to make a big family. My first wife found my second wife for us because she was also looking to have many children." This sounds like quite a lot of work, and "work" (the Aka word - bila) is precisely how the Aka and Ngandu define sex sessions. As Aka people said, "The work of the penis is the work to find a child," and "Getting food is more difficult, but both are lots of work. Sex life is not as tiring as work during day; the work at night is easier because you can make love then sleep." Although some Aka younger couples reported having sex in the forest, we can see here how strongly their social values about work and creating a family are attached to their domestic sleep patterns. In fact, how Aka people build their houses is related as well, as they are designed specifically for a place to do these night-time activities (and not too much else). As Boyette and Hewlett 2 mention, "Aka houses are used only for sleeping, are placed 0.3 to 1.22m apart on average, and have enough room for a hearth fire and a bed (Hewlett et al. 1998)."
So generally if you're in a society such as this, where your house is small and of perishable materials, then you'd have developed/inherited a sleep pattern which lets you (or someone in your house) wake up to tend the fire. Some societies don't do this, and so sleep through it and awake to the fire being smoldering embers. But for those societies who do, their sleep patterns are changed:
Fire also produces steady, irregular (in volume, frequency, and quality) noise that some ethnographers report as being subliminally monitored in sleep: continual small noises are reassuring, loud pops are arousing, and the absence of sound wakes the sleeper concerned with fire maintenance. The presence of the flicker and the faint glow from the fire is reported as comforting and soothing or hypnotic, conducive to sleep during periods of nighttime insomnia, and facilitative of reassuring visual scans of the sleeping space.
That lengthy paper by Worthman & Melby has more information on looking at how peoples around the world sleep, but generally it's going to be quite different from what you are likely to have experienced (if you are European or Euro-American). While Euro-Americans allow their pets such as dogs and cats to sleep with them, they often don't let children sleep directly with them. This is the opposite in the rest of the world, where pets are more often ejected and babies allowed. "It's pretty much universal that babies don't sleep alone. They either lie right next to their mothers, or nearby on a mat, or in a cradle or a sling," notes Carol Worthman 4. This is called co-sleeping and is found in many parts of the world, being done after infancy as well. As Hewlett & Roulette 5 summarize: "...[it] may be common in the high fertility mortality small-scale cultures that characterized most of human history." But specifically, the Hewlett's and others 6 have focused on Congo basin central African foragers and farmers. These societies simply have a lot of "emotional proximity."
Forager camps are generally very dense, often occupying a space the size of a large dining and living room in the USA or the space of one or two [Bantu speaking] farmer houses. When hunter-gatherers sit down in the camp, they are usually touching somebody. At night, foragers sleep very close together and usually sleep with someone; our study of co-sleeping found that forager children and adolescents never slept alone."
...the number and composition of sleepers in the small (about 2 meters in diameter) leaf huts of Efe foragers vary, but virtually no one sleeps alone, and one may routinely find two adults, a baby, another child, a grandparent, and perhaps a visitor sleeping together in the small space. Two or three sleep along the back of the hut, one of either side of the fire, and another one or two around the edges. Degree of physical contact is high, with full body contact and frequent entwining of appendages of two or three sleepers, along with periodic arousals associated with rearrangement movement of others, noises (cries, sniffs, snores, etc.), and traffic associated with staggered bedtimes and occasional elimination...
This is a historically documented practice as well, the Khoi pastoralists of southern Africa are shown co-sleeping in a large group 7 as seen in a racist popular anthropological overview from 1878. As mentioned on page 233, he notes their ability to sleep at any time, "it is almost impossible to place him [a Khoi person] under conditions in which he will not sleep." He notes that this curled up and co-sleeping arrangement is different compared to nearby Bantu speaking farmers, who sleep in their houses as families on laid out beds. While unverifiable, he notes that a Khoi person will sleep if they are hungry and have to wait til they can get or make food later.
I am hardly an expert on medieval sleep, but I can provide two bits of evidence from our early medieval Latin sources. There appears to have been some kind of wakefulness in monastic contexts as the Benedictine rule spread. However, it is well after midnight, closer to morning. Additionally, Bishop Isidore of Seville describes the names for parts of the night in ways that do not suggest that that night was meant to be wakeful. I'll add one more bit of evidence from a completely different medieval context at the end (I specialize in Norse, so I gotta talk about the sagas, it's contractually obligated, sorry).
Disclaimer: This by no means settles the debate: I suspect that there's a lot of variation across medieval Europe hidden in the primary evidence.
Still: in favor of the biphasal sleep schedule, we have the Rule of St. Benedict, one of the, if not the, dominant guidelines for monasteries for most of the Middle Ages. In Chapter 4, one of the "good works" it lists is "Non somnulentum" [not to be prone to sleep]. The Rule does not expand on this, and it could well indicate that sleeping in until noon was frowned upon, but it at least goes so far as to say that there is a thing as too much sleep. However, in Chapter 8, the Rule states:
De officiis divinis in noctibus
Hiemis tempore, id est a kalendas novembres usque in Pascha, iuxta considerationem rationis, octava hora noctis surgendum est, ut modice amplius de media nocte pausetur et iam digesti surgant. Quod vero restat post Vigilias a fratribus qui psalterii vel lectionum aliquid indigent, meditationi inserviatur. A Pascha autem usque ad supradictas novembres sic temperetur hora, ut Vigiliarum agenda parvissimo intervallo, quo fratres ad necessaria naturæ exeant, mox Matutini qui incipiente luce agendi sunt, subsequantur.
"On the divine offices [i.e. prayers] at night.
In wintertime, that is from the Kalends of November until Easter, as determined by rational computation, rising should be at the 8th hour of the night [roughly 3 am], and it ends a more full length [of rest] from midnight and now they may rise well-rested. And that which truly remains after vigil be devoted to meditation by the brothers who need to know something of the psalms or lessons. From Easter however, until the above mentioned date in November let it be arranged at such an hour, that a very short interval from the ending of Vigil having passed, in which the brother may deal with the necessities of nature, soon the Matins, which beginning at the first light, may follow." [Translation mine, errors also mine. My Latin is rusty.]
So, this indicates that monastic context actually did not get up at midnight and go back to bed. They got up closer to dawn, did the night prayers, and then stayed up. Side note: I would have died if I had to do that; I am NOT a morning person].
Anyway, let's add onto that Isidore of Seville. In his Etymologies, which were hugely popular in the Middle Ages, he outlines all the parts of the night: "vesper, crepusculum, conticinium, intempestum, gallicinium, matutinum, diluculum". The one of interest is Intempestum, literally "un-timed"
He describes this time of night as "intempestum est medium et inactuosum noctis tempus, quando agi nihil potest et omnia sopore quieta sunt. Nam tempus per se non intellegitur, nisi per actus humanos."
"Un-timed" is the middle and inactive time of night, when nothing is able to be done and everything is quieted by sleep. For time is not understood by itself, except through the deeds of humans.
This is a pretty clear indication that the dead of night in the early 7th century was understood as a time when nobody should be doing things. Everyone's supposed to be asleep to witness the passing of time. So, no biphasal sleep here.
Now, one more example: in 13th century Iceland, the norm appears to have been mono-phasal sleep. Ambushes tend to take place right around midnight in Sturlunga saga, such as one case where the enemies of Sturla Sighvatsson break into his house looking for him (he was visiting a friend that night, whoooops). Everyone except the attackers are asleep, so they were able to get the jump on the farm. Similarly, at the burning of Gizur Thorvaldsson's farm at Flugumyri, the fire was set at night, and initially everyone inside the on-fire farmhouse rolled over and went back to sleep. It took the smoke getting pretty thick to rouse people, which we would not necessarily expect if people were accustomed to rising during the night en masse. (often, it's people getting up to pee that ends up being the warning of nighttime ambushes in Old Norse literature, which I think is hardly evidence of a regular waking time in the middle of the night.)