Sleep Twice A Day: The Optimal Pattern For Ultimate Rest

Biphasic sleep involves two sleep periods: a longer nighttime sleep and a shorter daytime nap. This sleep pattern was common in pre-industrial societies, but the Industrial Revolution and the advent of artificial lighting led to the monophasic sleep pattern that is now dominant. While some people still adopt biphasic sleep to increase productivity and reduce the effects of lost sleep, there is limited scientific evidence of its benefits.

The benefits of biphasic sleep

Biphasic sleep is a sleep pattern that involves two distinct periods of sleep within a 24-hour cycle. This type of sleep schedule is believed to be more aligned with our natural sleep patterns and the sleep patterns of many animals. While it may not be suitable for everyone, there are several potential benefits to adopting a biphasic sleep pattern.

Improved Sleep Quality

Many people who follow a biphasic sleep schedule report deeper sleep and feel more refreshed upon waking. This may be because the shorter sleep period allows for more time in the deeper, more restorative stages of sleep.

Increased Productivity

Following a biphasic sleep pattern can lead to increased productivity during the day. The shorter sleep periods result in more time spent awake and alert, and the body's natural circadian rhythms align better with this type of sleep pattern. This can be especially beneficial for those who need to get up early or have irregular work schedules.

Greater Flexibility

Biphasic sleep provides greater flexibility, making it easier to fit sleep into a busy schedule. This can be advantageous for individuals with early mornings or those who work irregular hours, such as night shifts.

Improved Brain Function and Energy Levels

Research indicates that biphasic sleep schedules with a short midday nap and a long nighttime sleep may enhance brain function and energy levels. Short naps of under 30 minutes are known to boost energy and alertness, improving thinking and reasoning abilities.

Reduced Risk of Sleep Debt

Biphasic sleep can help individuals who don't get sufficient sleep at night to accumulate more sleep overall. This includes people who work night shifts or experience sleep deprivation due to sleep disorders or other disturbances.

Health Benefits

A large study of Mediterranean adults found that those who took 30-minute naps as part of a biphasic sleep schedule were 21% less likely to have high blood pressure than those who didn't nap.

Historical and Cultural Relevance

Biphasic sleep was likely the typical sleep pattern for humans before the Industrial Revolution and the advent of electric lighting. Records indicate that individuals would sleep shortly after sunset, wake up for an hour or two, then return to sleep. This type of sleep pattern is still prevalent in cultures that observe midday siestas, such as in Spain, Italy, and Greece.

The history of biphasic sleep

Biphasic sleep, or sleeping in two distinct periods over 24 hours, was the norm for much of human history. The ancient Egyptians are often credited with being the first civilisation to adopt this sleep pattern, with evidence dating back to at least 2000 BCE. The Egyptians 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. This pattern was described by the Roman historian Plutarch, who wrote that the Egyptians "interpose a set of leisure hours between the two periods of sleep."

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 was still practised 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.

In the early modern period, biphasic sleep began to fall out of favour as the Industrial Revolution led to a shift towards a more standardised sleep schedule. The rise of factories and the need for a consistent workforce led to the adoption of a monophasic sleep pattern, with a single block of sleep at night. This shift was also influenced by the growing belief that biphasic sleep was a sign of laziness and a lack of discipline.

Despite the widespread adoption of monophasic sleep, biphasic sleep has experienced a resurgence in recent years as research has shown that it can have numerous health benefits. Studies have found that biphasic sleep can improve mood, increase productivity, and even reduce the risk of certain health conditions.

One of the main benefits of biphasic sleep is the longer period of wakefulness during the day, which can increase productivity and creativity. This is because the brain functions better during the daytime when exposed to natural light, as this helps to regulate the body's internal clock. Biphasic sleep can also improve mood by allowing for a longer period of rest and relaxation during the day, reducing stress and increasing feelings of well-being.

In terms of physical health, biphasic sleep has been linked to a number of benefits. For example, research has shown that taking a midday nap can lower blood pressure, reduce the risk of heart attacks and strokes, and even boost the immune system. Biphasic sleep has also been found to improve athletic performance and reduce the risk of accidents, as it allows for a longer period of rest and recovery.

Today, biphasic sleep patterns can still be observed among people all over the world, despite widespread access to electricity. Nearly one-third of people in the United States report taking a nap every day, and in Japan, it is widely accepted that taking a brief nap during work hours improves morale and productivity. Afternoon siestas, though less common than in previous generations, are still practised in many Mediterranean and South American countries. In Muslim cultures, some people segment sleep with a long nighttime awakening or a long afternoon nap to accommodate daily prayer rituals.

The downsides of biphasic sleep

While biphasic sleep may be a natural pattern for some, it is not without its drawbacks. Here are some of the potential downsides of biphasic sleep:

• Sleep deprivation: One of the main concerns with biphasic sleep is the potential for sleep deprivation. This can occur if the sleep periods are too short or interrupted, or if the individual struggles to fall asleep or maintain quality sleep during the two segments. Sleep deprivation can lead to serious health problems, including an increased risk of heart disease, kidney disease, diabetes, stroke, high blood pressure, obesity, and depression. It can also impair cognitive performance and increase the risk of injuries and accidents.
• Sleep inertia: Biphasic sleep can lead to sleep inertia, which is the feeling of grogginess and disorientation after waking up. This can impact an individual's performance and reaction time, making it challenging to carry out daily tasks or work-related activities.
• Difficulty falling asleep: Sleeping more than once per day may disrupt an individual's sleep drive, making it more challenging to fall asleep or stay asleep during the two sleep periods. This can be especially true for those who already experience difficulty sleeping, such as those with insomnia.
• Social and work obligations: Adhering to conventional work or school schedules, which typically require individuals to be awake during the majority of daylight hours, can make it difficult to fit in a biphasic sleep schedule. Social attitudes towards napping, particularly in North America, can also create barriers to finding time and space to nap during the day.
• Negative impact on overall sleep quality: Research on segmented sleep has found that individuals who practice biphasic sleep are more likely to report poorer sleep quality and increased daytime sleepiness. This may be due to changes in how the body regulates sleep homeostasis and the circadian rhythm.
• Not a cure for sleep disorders: While biphasic sleep may be a natural pattern for some, it is important to note that it is not a cure for sleep disorders such as insomnia. Individuals with sleep disorders should seek professional medical advice rather than self-prescribing a course of treatment.
• May not suit all work schedules: Biphasic sleep, especially if it involves long afternoon naps, may not be feasible for individuals with strict work schedules or caregiving responsibilities. However, nighttime biphasic sleep, where both sleep sessions occur at night, could be a potential alternative.
• Potential health risks: Some studies have linked napping to an increased risk of cardiovascular disease and cognitive decline in older adults. Napping for longer than 30 minutes can also lead to a state of confusion and grogginess upon waking, reducing the restorative benefits of sleep.

How to transition to biphasic sleep

Biphasic sleep is a sleep pattern that involves two separate periods of sleep over 24 hours. This usually takes the form of a midday nap and a longer nighttime sleep.

If you're interested in transitioning to biphasic sleep, here are some tips to help you make the change successfully:

• Choose a biphasic sleep schedule that suits your lifestyle: Select a biphasic sleep pattern that fits your work schedule, environment, and social life. For example, if you work in the evenings and want to improve your focus, a short midday nap might be beneficial. If you have trouble sleeping through the night, try a first and second sleep pattern.
• Be consistent: Try to nap at the same time every day and maintain a regular sleep schedule for both your nap and nighttime sleep. This will help your body adjust to the new routine.
• Limit your exposure to artificial light: Reduce your exposure to artificial light from phones, TVs, computers, and tablets for at least 30 minutes to an hour before your nap or nighttime sleep. If you follow a first/second sleep schedule, avoid bright lights during your waking hour.
• Create a sleep-friendly environment: Sleep in a dimly lit or dark room to facilitate daytime sleep. Keep your bedroom dark, quiet, and cool for optimal sleep.
• Practice good sleep hygiene: Stick to a regular sleep schedule, eat well, and exercise during the day. Avoid caffeine, and follow a calming bedtime routine to relax before sleep.
• Monitor your results: Pay attention to how you feel throughout the transition. Assess whether you feel more alert and focused or more groggy. If biphasic sleep doesn't improve your rest, it may be best to stick to a monophasic schedule.

The difference between biphasic and polyphasic sleep

Biphasic sleep refers to a person sleeping twice in a 24-hour period. This is sometimes called a siesta sleeping pattern, where the longest stretch of sleep is usually at night, lasting 5-6 hours, followed by a shorter rest in the afternoon, lasting 60-90 minutes. Another type of biphasic sleep pattern is the first/second sleep schedule, where a person has their first sleep around 9 or 10 pm, wakes up for an hour or two, and then goes back to sleep. The goal is to get at least seven hours of sleep in total.

Polyphasic sleep, on the other hand, involves multiple sleep segments or more than two sleeps per day. This is a pattern with more than two sleeping periods throughout the day. Polyphasic sleep reduces nighttime sleep and involves multiple daytime naps. Some common polyphasic sleep schedules include the Uberman Sleep Schedule, where a person takes six 20-minute naps throughout the day, and the Everyman Sleep Schedule, where a person sleeps for three hours at night and takes three 20-minute naps during the day.

The terms "segmented" or "divided" sleep can refer to either biphasic or polyphasic sleep. However, biphasic sleep specifically describes a sleeping schedule with two segments, while polyphasic sleep involves more than two sleeping periods.

There is no scientific evidence that polyphasic sleep is effective or beneficial, and it may even have adverse physical and mental health consequences. Biphasic sleep, on the other hand, has been found to have some benefits, such as improved alertness and cognitive performance, but the overall evidence is mixed, and further research is needed.

Both biphasic and polyphasic sleep patterns were more common before the Industrial Revolution, when artificial lighting became widely available and the modern workday was established. Today, monophasic sleep, or sleeping once per day, is the most common sleep pattern.

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