Biphasic sleep is a sleep pattern where a person rests in two separate periods within a 24-hour day. Instead of sleeping all at once at night, sleep is divided into two segments.
Today, most people follow a monophasic sleep schedule, which means sleeping in one continuous block of about seven to nine hours. However, before the Industrial Revolution, it was common for people to sleep in two parts, often called first sleep and second sleep, with a period of wakefulness in between.
Biphasic sleep reflects a natural rhythm in which energy levels rise and fall throughout the day. This pattern is still seen in some cultures and may align with the body’s internal clock, especially during the early afternoon dip in alertness.
How biphasic sleep works
Biphasic sleep differs from monophasic sleep because it divides rest into two periods instead of one continuous stretch. In a monophasic schedule, a person typically sleeps from late evening until morning without interruption. In a biphasic schedule, sleep is split across the day or night.
Siesta pattern
The siesta model includes a shorter period of sleep at night, usually around five to six hours, combined with a daytime nap that lasts between twenty and ninety minutes. This pattern often aligns with the natural drop in energy that many people feel in the early afternoon.
First and second sleep pattern
The first and second sleep model reflects historical sleep habits in which people slept in two segments during the night. In this pattern, a person sleeps for several hours, wakes for one to two hours, and then returns to sleep for another few hours before morning.
Potential benefits
The benefits of biphasic sleep can include:
1. Improved alertness
Biphasic sleep may help improve alertness, especially during the afternoon when many people experience a natural drop in energy. A short and well-timed nap can restore focus and reduce feelings of fatigue.
2. Memory consolidation
Sleep plays an important role in memory consolidation, which means that the brain processes and stores information more effectively after rest. Even short naps may support learning and cognitive performance.
3. Stress reduction
Midday rest may help reduce stress by allowing the body to recover from mental and physical strain. Some research suggests that napping can help regulate stress-related hormones and promote relaxation.
4. Adaptability
Biphasic sleep can be more adaptable for people with flexible schedules, such as students or those who do not work traditional hours. It allows sleep to be distributed in a way that better fits individual daily routines.
Possible risks and side effects
Despite its potential benefits, biphasic sleep may also have some drawbacks. One common issue is sleep inertia, which is the feeling of grogginess and confusion that can occur after waking from a nap, especially if the nap is too long or interrupted. This can make it difficult to return to normal activities right away.
Daytime napping may also increase the risk of insomnia in some individuals. If a nap reduces the body’s need for sleep at night, it can become harder to fall asleep or stay asleep during the main sleep period. Another concern is disruption of the circadian rhythm, which is the body’s internal clock that regulates sleep and wake cycles. If sleep times are inconsistent or poorly timed, this rhythm can become misaligned, leading to fatigue and sleep difficulties.
Who should and shouldn’t try biphasic sleep
Biphasic sleep may be a good option for people who have flexible schedules or who naturally feel tired in the afternoon. This includes students, remote workers, and individuals who can adjust their daily routine to include a planned nap. It may also suit people who find that a single block of sleep does not leave them feeling fully rested.
However, biphasic sleep may not be appropriate for everyone. People with chronic insomnia or sleep disorders such as sleep apnea may find that changing their sleep pattern worsens their symptoms. It may also be difficult for individuals with strict work schedules, especially those who cannot take breaks during the day, to maintain a consistent biphasic routine.
Step-by-step how to transition to a biphasic schedule
Transitioning to a biphasic sleep schedule requires consistency and careful planning to help the body adjust smoothly.
- Maintain a consistent schedule by going to bed and waking up at the same times every day so your body can adapt to a stable rhythm.
- Keep the daytime nap short at around twenty minutes or extend it to about ninety minutes to complete a full sleep cycle and reduce grogginess.
- Create a comfortable sleep environment by ensuring the room is dark, quiet, and cool for both sleep periods.
- Use light exposure to your advantage by getting natural sunlight during waking hours and limiting bright light and screens before sleep.
Following these steps can make it easier to adapt to a biphasic sleep pattern while maintaining good sleep quality.
When to see a doctor
If you continue to feel tired or unrefreshed despite adjusting your sleep schedule, it may be a sign of an underlying health issue rather than a problem with your sleep pattern. Persistent fatigue can be linked to conditions such as anemia, thyroid disorders, or sleep-related illnesses. In these cases, it is important to seek medical advice to identify and treat the root cause.