時程編排概述
睡眠安排涉及許多方面，是一個複雜的話題，必須根據個人的需要進行調整。如果多相睡眠時程設計得不好，十之八九會導致嚴重的睡眠不足，而且很可能一直無法適應，浪費幾週甚至幾個月的時間。這頁會詳細介紹目前關於多相時程編排的共識。
睡眠階段
睡眠是一種會為身體整體帶來生理上的變化的複雜現象。然而，它主要影響的是大腦。根據大腦中的電活動，睡眠被分為快速動眼期（REM）和非快速動眼期（NREM）。NREM睡眠根據腦電波的頻率和振幅再被進一步分為三個階段。
NREM第一階段佔單相成人總睡眠的5-10%，是所有NREM階段中最淺的睡眠階段。在這個階段中，對外部環境和對自身的意識都會有所減弱。部分人在這個階段會出現抽搐或臨睡幻覺。NREM1中Alpha波和Theta波會混合存在。
NREM第二階段是比第一階段更深的睡眠，佔總睡眠的45-55%。與NREM1相比，在NREM2中更難被喚醒。這個階段的特徵是K-複合波和 睡眠梭狀波，即Alpha波活動的突然中斷。這階段的睡眠也負責維持長時間的清醒狀態。
NREM Stage 3, accounting for 15-25% of total sleep, is the deepest of all sleep stages. This stage contains primarily delta waves, which are high-amplitude and low-frequency. Hence, this stage is also known as slow-wave sleep (SWS). It is very difficult to wake up from this stage; attempts at doing so tend to result in sleep inertia -- a period of intense grogginess and impaired cognitive function. This stage of sleep plays a critical role in the maintenance of the brain through the glymphatic system. This process takes about 30 to 60 minutes of continuous NREM3 to complete, and could be hindered by schedules containing only short naps.
REM, accounting for 20-25% of total sleep, is characterized by high frequency, low amplitude activity that resembles that during wakefulness and rapid eye movements. In this stage, muscles are also paralyzed and body temperature becomes unregulated. Vivid dreams are also often experienced during this stage, and the muscle atonia (paralysis) prevents the sleeper from acting them out.
透過多相睡眠削減睡眠
SWS and REM (collectively termed vital sleep stages) are the most necessary for the body, and in general cannot be cut. When a sleeper does not get a sufficient amount of SWS or REM, the respective pressure starts to build up. As the pressure builds, the body starts to favour that kind of sleep over others. At some point, this can lead to sleep-onset REM (SOREM) and sleep-onset SWS (SOSWS), which enables a sleeper to gain the required amount of SWS and REM in a shorter amount of time. Moreover, when sleep is restricted, vital sleep stages displaces light sleep (NREM 1 and 2), which further reduces the amount of total sleep needed to sustain the body.
However, as NREM 2 gets reduced, the ability to stay awake for long periods diminishes. This is why schedules with less total sleep time (TST) need more sleeps spread throughout the day to be sustainable. Taking a ~20-minute nap or a ~90-minute single-cycle core helps a polyphasic sleeper sustain wakefulness. Maximum wake gaps are dependent on the schedule, time of day, as well as the sleeper's individual needs. With gaps too large, one will always experiences bouts of tiredness during it and be unable to fully adapt to the schedule.
晝夜節律
The circadian rhythm is the body clock aligned to local solar time by light exposure and food intake, among other factors. It generates hormonal changes throughout the day consistently to produce effects on the body. One of the main effects is the secretion of melatonin, the presence of which is essential for entering SWS, and also affects the timing of REM sleep.
After sunset when light levels reduce, the body starts to secrete melatonin to promote sleep. The rising levels of melatonin early in the night allows the body to gain SWS in the first few sleep cycles. In contrast, as melatonin levels drops in the morning, REM becomes the preferred sleep phase to be gained.
In modern times with the advent of artificial light, many people's circadian rhythms have been pushed forward (i.e. later). However, this exposure to artificial light sources also compromises people's ability to gain SWS efficiently. The extent to which light influences the circadian rhythm is given by the melanopic light sensitivity function, which peaks at ~480nm (blue) and drops off on both sides. To reduce this effect, a dark period must be employed, during which blue and green lights must not enter the eye. This can be done in many ways, such as with red goggles or screen filters.
To maintain the stability of the circadian rhythm, all polyphasic sleep schedules must stay relatively consistent day-to-day, without large changes in core or dark period timings. As such, schedules that are not aligned with the 24-hour day are unsustainable and unhealthy. Examples of which includes cycles longer than 24 hours (delaying sleep phases continually) or employing drastically different sleep schedules on a day-to-day basis.
睡眠量下限
由於必要睡眠階段一般不能被減少，所以隨著總睡眠時間的減少，維持一個時程所需的壓縮程度也會急劇增加。然而，壓縮睡眠是需要適應的，而更大程度的壓縮則需要更嚴厲和/或更長的適應時間。因此，時程可以根據其睡眠減少的程度進行適應難度的分類。
值得注意的是，年輕人的大腦和身體仍在發育，比成年人需要更多的SWS和REM，這會增加他們的睡眠量下限，使減少睡眠更加困難。此外，NREM2被認爲在大腦發育中可能帶有其他功能，因此削減NREM2可能會對發育有潛在的問題。
| 年齡 | 建議最低睡眠量 |
|---|---|
| <16 | 7.5小時 |
| 16-18 | 6小時 |
| 18-21 | 5小時 |
| >21 | 4小時 |
爲了防止對健康產生不良影響，我們建議將睡眠在任何時候都保持在這些限度以上。必要睡眠階段的必要性也意味著某些時程，像是Uberman或Dymaxion等等，因為其總睡眠時間低於大多數人所需的必要睡眠時間，對大多數人來說是無法實現的。
以下是以一個典型的睡眠者有8小時的單相睡眠及正常的SWS和REM水平為假設，按難度對時程作出的基本分類：
| 難度 | 時程示例 | TST範圍 | 睡眠削減量 | 備注 |
|---|---|---|---|---|
| 簡單 | 二相X，E1-延長，Siesta-延長，分割-延長 | 7-8小時 | <1小時 | 推薦給新手或需要大量彈性的人。 |
| 中等 | E1，E2，E3-延長，Siesta，DC1，Triphasic-延長，分割, DC1-延長 | 5-6小時 | 1-2小時 | 需要一個體面的適應過程，但適應後可以有相當的彈性。 |
| 困難 | E3，DC2 | 4-5小時 | 2-3小時 | 需要苛刻的適應過程，對大多數人來說不是特別靈活 。 |
| 非常困難 | DC3，Bimaxion，三相 | 4-5小時 | 2-3小時 | 因為它們在SWS高峰期間中沒有較長的主段，因此被認為比“困難”的更難。 |
| 極度困難 | E4，E3-縮短，Uberman，Dymaxion | <4小時 | >4小時 | 被認為對大多數人來說是不可能的。 |
睡眠段落長度
Cores are long blocks of sleep that contain at least one full sleep cycle. They are typically scheduled to be a multiple of a 90 minutes, which is a common sleep cycle length. However, alternative core lengths can be done to either to plan for alternative cycle lengths or in an effort to gain extra time in SWS or REM. Cores are generally considered to be essential, because they provide the necessary amount of SWS to sustain life. As such, schedules without cores (i.e. nap only schedules) have extremely low success rates.
Naps are short blocks of sleep, typically about 20 minutes on default schedules. Naps allow for a small amount of REM to be gained. Moreover, naps help sleepers sustain wakefulness through gaps. Longer naps (up to ~45 minutes, known as pronaps) can be used in during the REM peak around dawn to gain even more time in REM. Longer naps in other times of the day can lead to SWS wakes, which can be exceptionally difficult to wake from for some people, especially during periods of high SWS deficit.
Core sleeps are favoured during night time, as they allow sufficient time to complete SWS-filled sleep cycles. They are also easier to schedule at night for most people due to social obligations. Naps are favoured in the day, since deeper sleep stages are less likely to appear then. After adaptation, naps can be relatively flexible, whereas cores are much harder to move.
一致性
During adaptation, most polyphasic schedules (other than non-reducing ones) are strict, that is, they must be done very consistently, without missed sleeps, moved sleeps, oversleeps, or undersleeps. If your life schedule cannot accomodate the sleep schedule you are planning for almost all days, it is unlikely that you will ever be able to adapt to it. One or two minor mishaps should not cause too much damage to your adaptation. However, as the mistakes accumulate, your chance of successful adaptation decreases. It is therefore necessary to plan ahead and avoid these mistakes, by carefully scheduling your life around the sleeps as well as setting proper alarms to avoid oversleeps.
時程類別
自古以來，人類遵循的時程主要有兩種：晚上有兩個長的睡眠，中間有一個醒來的間隙的分割睡眠，以及晚上一個長的睡眠，下午一個短的睡眠的Siesta。當然，古人的時程安排更加靈活，因此很可能比目前的標準時程有更長的總睡眠時間。目前大多數多相睡眠時程都是從單相睡眠以及上述兩種歷史上常見的時間表演變而來的。
二相時程的類別以上述的兩個歷史上的多相時程，以及可以被認爲是Siesta的變體的E1而構成。
Everyman時程的類別是通過去除單相睡眠結束時的睡眠週期，並增加小睡來彌補失去的REM和維持清醒而形成的。
雙主段時程的類別也是如此，只不過它使用分割睡眠代替單相睡眠。
幾十年來，多相睡眠社群已經開發了幾種已知道有效的時程類別。
| 時程類別 | 説明 | 備注 |
|---|---|---|
| 二相 | 兩次睡眠 | 通常被認爲最簡單，常被推薦給新手嘗試。 |
| Everyman | 一次主段睡眠和兩次或以上的小睡 | |
| 雙主段 | 兩次主段睡眠和一次或以上的小睡 | |
| 三主段 | 三次主段睡眠 | |
| 僅小睡 | 沒有主段，小睡次數無限制 | 對於大多數人來説無法實行。 |
| 實驗性質 | 不屬於以上類別的時程 | 由於可行性的證據不足，通常不建議新手進行嘗試。 |
