Random
Random sleep is irregular sleep, which has no structure, changes from day to day and can't be categorized into any current specific sleep patterns.
Mechanism
Random is a highly popular sleep pattern, which has plenty of variants. Since it inherently has no rules, such schedule would fit any lifestyle. Sleep may be taken whenever possible or tired enough.
One of the characteristics of Random sleep is a level of randomness, which may be higher or lower. This characteristic can be generally defined in every sleep pattern. The lowest possible level of randomness is a strict consistent schedule. Polyphasic schedules usually tolerate some flexibility after adaptation, which makes the level of randomness higher. The highest level is observed in BiphasicX and -Amayl schedules, which don't have fixed sleep times and / or fixed length of sleeps. The Random category, on the other hand, allows a much higher level of randomness, such as an absolute absence of sleep structure.
Dark period and circadian rhythm management is optional.
Random sleep was observed to cause several negative consequences, which are described below.
Variants
Irregular sleep includes multiple subpatterns, which have different total sleep time, level of randomness and structure. Some of the schedules, which have a higher level of randomness, were previously considered random, but after a few successful adaptations were separated from the Random category. This includes BiphasicX and -Amayl schedules. However, each of these schedules is based on a specific set of rules (for example, Ducamayl has 2 cores and a few naps each given day), which would make them Hypothetical rather than Random from the very beginning.
Thus, the variants of Random are the observed patterns of random sleepers, which may be combined with each other and not be consistent.
Mono-polyphasic hybrid
One of the mildest patterns of Random is a fairly consistent long nocturnal core, which doesn't reduce sleep and sometimes is supplied with naps in the energy dips during the day. Such sleep is mostly non-reducing. If the naps are short, this resembles Sevamayl, except having occasional monophasic days without naps. The sleep quality may be increased further by adding a dark period 2h prior the core.
Frequent switching between schedules
It's possible to stay on Random involuntary by switching sleep schedules frequently. This pattern was observed in individuals, who couldn't maintain one sleep schedule consistently for a long time, thus switching between different monophasic and polyphasic schedules every other day.
Sleeping in on weekends
This pattern is very common, although not necessarily belongs to the Random category by itself (e.g. consistently having a monophasic core, which is longer on weekends). However, most commonly this pattern is inherent in random sleepers. It was observed in different studies that weekend catchup sleep does not fully compensate for high rates of sleep debt and short sleep on weekdays[1], often keeping the effects of sleep deprivation, such as metabolic dysregulation[2], which leads to excessive eating and obesity. Thus, it's highly recommended to have a consistent total sleep time throughout the week.
Short chunks of sleep
Consequences
References
[1] - Lv Y, Cai L, Zeng X, et al. Association between weekend catch-up sleep and executive functions in Chinese school-aged children. J Clin Sleep Med. 2020;16(8);1285–1293.
