Napping Twice Daily: Is It Healthy Or Harmful?

The concept of segmented sleep, or biphasic sleep, is not new. In pre-industrial times, it was common to sleep in two shifts, with a couple of waking hours in between. In the modern world, this is often referred to as polyphasic sleep, which involves sleeping in multiple periods over 24 hours. While some people adopt this sleep pattern to increase productivity, there is limited research on its effectiveness and potential health benefits or detriments.

Biphasic sleep involves two sleep periods: a longer night-time sleep and a shorter daytime nap

Historically, biphasic sleep was the norm in pre-industrial societies. In the Middle Ages, people would sleep in two distinct phases, bridged by an intervening period of wakefulness of approximately one hour. This time was often used to pray, reflect, and socialise. The two periods of night sleep were called "first sleep" and "second sleep" in medieval England.

In modern times, biphasic sleep is still practised in some parts of the world. For example, the siesta is a traditional biphasic sleep pattern in Spain, Italy, China, India, South Africa, Greece, and some countries in South America and the Middle East.

There are different variations of biphasic sleep schedules. The siesta sleep schedule involves a 60- to 90-minute nap in the afternoon, followed by five to six hours of sleep at night. The midday nap sleep schedule involves a 20- to 30-minute nap during the day and six to seven hours of sleep at night. The first/second sleep schedule is the original biphasic pattern from the preindustrial era, where people would sleep for a few hours, wake up for an hour or two, and then sleep for a second phase.

While some people find biphasic sleep beneficial, there are potential downsides. Biphasic sleep may not be feasible for those with strict work schedules or family commitments. Additionally, there is a risk of sleep deprivation if the total sleep time across the two periods is insufficient.

Segmented sleep is also known as biphasic sleep and is common in pre-industrial societies

Segmented sleep, also known as biphasic sleep, is common in pre-industrial societies. In fact, the practice of sleeping in two shifts was common for millennia, with references to biphasic sleep found in literature from the 8th century BC to the early 20th century.

Biphasic sleep typically involves a longer night-time sleep and a shorter daytime nap. In pre-industrial times, people would go to bed early in the evening, wake up a couple of hours later, and then return to bed for a second period of sleep in the morning. This period of wakefulness in the middle of the night was known as "the watch".

The practice was common across the pre-industrial world, with references to biphasic sleep found in cultures as distant as Africa, South and Southeast Asia, Australia, South America, and the Middle East. In France, the initial sleep was called the "premier somme", while in Italy, it was the "primo sonno".

During "the watch", people would tend to ordinary tasks such as adding wood to the fire, taking remedies, or going to urinate. It was also a time for religion, with specific prayers prescribed for this time. It was also a time for socialising and intimacy, with bedfellows taking advantage of the casual informality of the moment.

The shift from biphasic sleep to monophasic sleep is largely attributed to the Industrial Revolution, with the advent of artificial lighting allowing people to stay up later. As people still needed to wake up at the same time in the morning, their rest was truncated and their sleep became deeper due to the compression.

While biphasic sleep is less common today, some people still adopt it to increase productivity and reduce the effects of lost sleep.

Polyphasic sleep involves sleeping over more than two periods each day

Polyphasic sleep involves breaking up sleep into multiple shorter periods throughout the day. This is in contrast to monophasic sleep, which is one period of sleep within 24 hours, and biphasic sleep, which involves two periods of sleep.

Polyphasic sleep is not the norm for most humans, who usually engage in monophasic sleep. However, polyphasic sleep is common in many animals and is believed to be the ancestral sleep state for mammals.

Polyphasic sleep can be further broken down into different types of sleep schedules, each with a unique pattern. Here are three of the most common polyphasic sleep schedules:

• Uberman Sleep Schedule: This is one of the most extreme forms of polyphasic sleep and involves six short naps, each lasting about 20 minutes, spread evenly throughout the day. This totals only two hours of sleep in a 24-hour period.
• Everyman Sleep Schedule: This schedule offers more flexibility than the Uberman schedule, as it includes one longer sleep period, usually lasting three to four hours, and two to three shorter naps spread out during the day.
• Triphasic Sleep Schedule: This schedule divides sleep into three distinct periods: a longer sleep at night and two shorter naps during the day. For example, someone following this schedule might sleep for three hours at night, take a 90-minute nap in the morning, and another 90-minute nap in the late afternoon.

Polyphasic sleep aims to tap into the most restorative phases of sleep more frequently, potentially making sleep more efficient. However, there is limited research on the efficacy of polyphasic sleep schedules, and there are potential risks and challenges associated with this type of sleep.

Monophasic sleep is the typical sleep pattern of most of the population

The shift towards monophasic sleep may have been influenced by the longer working hours of the industrial revolution. The modern industrial workday, which typically spans 8 hours, may have also contributed to the custom of sleeping for a single 6- to 8-hour segment per day.

While monophasic sleep is the most common sleep pattern, biphasic and polyphasic sleep patterns also occur naturally in some individuals. Biphasic sleep involves two sleep periods, typically a longer nighttime sleep and a shorter daytime nap. Polyphasic sleep, on the other hand, consists of multiple sleep segments throughout the day.

Some people may prefer biphasic or polyphasic sleep patterns as they believe it increases their productivity by providing more time for tasks and activities. However, it is important to note that changing sleep patterns can have potential health risks, and it is recommended to consult a doctor before making any significant changes to your sleep schedule.

The biphasic sleep pattern was common in the pre-industrial world

The practice of biphasic sleep, also known as segmented sleep or bifurcated sleep, was prevalent in various parts of the world, including France, Italy, Africa, South and Southeast Asia, Australia, South America, and the Middle East. In France, the initial sleep was called the "premier somme", while in Italy, it was referred to as "primo sonno".

The transition from biphasic sleep to monophasic sleep occurred during the Industrial Revolution due to the introduction of artificial lighting, such as gas lighting and electric lighting. This allowed people to stay up later, resulting in a compressed and deeper sleep.

The historian Roger Ekirch, author of 'At Day's Close: Night in Times Past', has extensively researched the topic of biphasic sleep in pre-industrial societies. Ekirch argues that the practice of interrupted sleep was dominant in Western civilization before the Industrial Revolution, citing evidence from more than 500 references in ancient, medieval, and modern documents.

While biphasic sleep may have been common in the past, it is important to note that today, most people follow a monophasic sleep pattern, sleeping in one continuous block during the night.

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