Napping Twice A Day: How And Why Some People Do It

Sleeping in two phases, also known as biphasic sleep, involves a person getting two sleep periods in a day. This could be two sleep sessions at night, or one sleep session during the day and one at night. While biphasic sleep is not common in the 21st century, it was more widely adopted before the late 19th century when Thomas Edison invented the lightbulb. Today, biphasic sleep is still relevant for people who work night shifts, those who are sleep-deprived, and those who care for babies. While there are benefits to biphasic sleep, there are also risks, such as sleep inertia, which can cause people to feel tired and groggy after waking up.

Biphasic sleep is a natural sleep pattern

Historical evidence suggests that biphasic sleep used to be the norm in many parts of the world, including Europe, Africa, North America, South Asia, Latin America, the Middle East, and Australia. People would usually go to sleep shortly after sunset, wake up a few hours later, and then return to sleep until morning. This practice is supported by anthropologist studies and historical records, such as a 16th-century doctor's manual from France recommending sex after the first sleep as the "best time to conceive."

The shift from biphasic to monophasic sleep is attributed to the advent of artificial lighting, which allowed people to stay awake and active for longer in the evenings. The industrial revolution further reinforced the move towards monophasic sleep, as people started forcing themselves to sleep through the night to conform to the demands of a standardized workday.

Today, biphasic sleep is still observed in some cultures, such as the siesta in Spain, Italy, and some Scandinavian countries. Additionally, certain individuals, such as shift workers, new parents, and students, may find themselves adopting a biphasic sleep schedule out of necessity.

While there are potential benefits to biphasic sleep, including increased productivity and improved cognitive function, there are also concerns about the potential for sleep deprivation and negative health impacts. Some researchers argue that biphasic sleep is unnatural and may disrupt circadian rhythms, leading to physical and mental health issues.

Overall, while biphasic sleep may work well for some individuals, it is not recommended for everyone, and it is important to prioritize getting sufficient, quality sleep to maintain overall health and well-being.

The rise of monophasic sleep

Monophasic sleep, where a person attains all their sleep in one block of time, usually at night, is the dominant sleep pattern today. However, this was not always the case. For much of human history, biphasic sleep, or sleeping in two distinct periods over 24 hours, was the norm.

The ancient Egyptians, as described by the Roman historian Plutarch, are often credited with being the first civilization to adopt a biphasic sleep pattern, with evidence dating back to at least 2000 BCE. They would sleep for four to six hours at night, then wake up for a period of rest or leisure activities before returning to sleep for another four to six hours.

Biphasic sleep was also common in ancient Greece, where it was known as "first sleep" and "second sleep." The Greek philosopher Aristotle wrote about biphasic sleep in his work "History of Animals," stating that it was a natural and healthy way to sleep. The Greeks would typically sleep for three to four hours, then wake up for a period of time before returning to sleep for another three to four hours.

During the Middle Ages, biphasic sleep became less common in Europe as the monastic practice of rising early for morning prayers became more widespread. However, it continued to be practiced by the general population in rural areas and among the working class. The word "siesta," which refers to a midday nap, comes from the Latin "hora sexta," or "sixth hour," as it was traditionally taken around noon, six hours after waking.

The shift towards monophasic sleep began in the early modern period with the Industrial Revolution. The rise of factories and the need for a consistent workforce led to the adoption of a monophasic sleep pattern. This shift was also influenced by the growing belief that biphasic sleep was a sign of laziness and a lack of discipline.

The development and widespread use of artificial lighting also played a significant role in the rise of monophasic sleep. With artificial light enabling people to stay up past sunset, humans gradually moved towards sleeping in a single stretch at night.

Today, monophasic sleep is considered the typical sleep pattern, with biphasic and polyphasic sleep patterns being less common. However, some people still adopt biphasic sleep in contemporary settings to reduce the effects of lost sleep and maintain productivity. Additionally, research has shown that biphasic sleep can have numerous health benefits, including improved mood, increased productivity, and reduced risk of certain health conditions.

The benefits of napping

Napping has been a common practice in many parts of the world, including Europe, Africa, North America, South Asia, Latin America, the Middle East, and Australia, until the late 19th century when Thomas Edison invented the lightbulb. Today, napping is still prevalent in Spain, Italy, China, and Scandinavian countries like Finland, Denmark, and Sweden.

Catching Up on Sleep

Napping can help individuals catch up on sleep when they are sleep-deprived, which can alleviate the negative consequences of sleep deprivation, such as worse mood and struggles with job or school performance.

Improved Cognitive Abilities

Midday napping has been consistently linked to improved cognitive performance, including better thinking, memory, and problem-solving abilities. Shorter naps of around 5 to 30 minutes can reduce sleepiness and cause immediate cognitive improvements, while longer naps of more than 30 minutes can provide cognitive benefits for a longer period.

Increased Physical and Mental Performance

Napping can increase physical and mental performance by improving alertness and reducing the risk of health conditions linked to sleep loss. This can lead to improved productivity and overall well-being.

Reduced Safety Risks

Sleep deprivation can increase the risk of accidents and impair an individual's ability to perform tasks safely. Napping can help reduce these safety risks by providing the body and mind with the rest they need to function optimally.

The downsides of biphasic sleep

Biphasic sleep, or sleeping in two segments per day, may not be for everyone. While some people find that biphasic sleep works well for them, there are some potential downsides to consider.

Firstly, following a biphasic sleep schedule may not be feasible for those with strict work schedules or other commitments, such as caregivers. Additionally, there is a risk of sleep deprivation if the total sleep time across the two segments is insufficient. Sleep deprivation can lead to serious health problems, including heart disease, kidney disease, diabetes, stroke, high blood pressure, obesity, and depression. It can also impair cognitive performance and increase the risk of accidents, such as drowsy-driving.

Some researchers argue that biphasic sleep is not natural and is influenced by external factors such as eating habits, social schedules, and afternoon temperatures. Furthermore, artificial light exposure at night, which is more common with biphasic sleep, can disrupt circadian rhythms and negatively impact sleep quality.

While biphasic sleep may offer benefits such as improved productivity and alertness, it is important to consider individual needs and preferences when deciding on a sleep schedule. Consistency, regular exercise, and good sleep hygiene practices are crucial for maintaining optimal sleep health, regardless of the sleep pattern followed.

Split sleep schedules and shift work

Split sleep schedules, also known as biphasic sleep, refer to sleeping in two segments per day. This could mean a longer nighttime sleep and a shorter daytime nap, or splitting nighttime sleep into two segments. In pre-industrial times, segmented sleep was common, with people waking up for a couple of hours in the middle of the night. This period was used for creative work, reading, or socialising.

Today, split sleep schedules are often adopted by shift workers, new parents, and students. However, it is unsustainable and may lead to sleep deprivation, which can cause serious health issues such as high blood pressure, depression, heart disease, diabetes, and obesity.

To successfully maintain a split sleep schedule, timing is crucial. Sleep should commence when there is a strong drive for sleep and during a low circadian point to quickly fall asleep and maintain sleep. Additionally, aiming for 8 hours of rest in lengthy blocks is recommended.

Split-shift schedules that maintain adequate sleep time may benefit shift workers' sleep, performance, and safety. Some industries have implemented shorter but more frequent sleep opportunities, such as 6 hours on/6 hours off, to reduce the time spent awake during shifts. While these schedules can provide flexibility and two periods of increased activity and alertness, they may not suit everyone's body clock or work schedule.

Shift work is associated with numerous negative health consequences and a higher risk of accidents and errors. Shift work disorder (SWD), a circadian rhythm sleep disorder, develops in a subset of shift workers, resulting in insomnia and excessive sleepiness. It is important to note that there is limited research on the long-term effects of split sleep schedules, and it may be challenging to implement split sleep schedules in real-world settings.

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