Circadian half-cycler

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Circadian half-cycler

Circadian half-cycler

A signal redirector which isolates half of the brain, allowing the other half to sleep while the user remains outwardly awake. By alternating brain halves, the user never needs to sleep. Unfortunately, two hemispheres are better than one - working half a brain causes a reduction in consciousness.

Base Stats

Medical ItemsBody Parts
Tech Level
Market Value
1030 Silver [Note]
4 kg


Crafted At
Fabrication bench
Required Research
Circadian influenceTechprint
Skill Required
Crafting 8
Work To Make
26,000 ticks (7.22 mins)
Resources to make
Plasteel 15 + Advanced component 4
Advanced, ImplantEmpireCommon
Bionic, ImplantEmpireCommon

The circadian half-cycler is an artificial body part that removes a pawns need to sleep at the cost of a permanent 15% Consciousness penalty.


Circadian half-cyclers can be crafted at a Fabrication bench once the Circadian influence research project has been completed. The required techprint can be obtained either by trade or completing quests for the Empire. They require Plasteel 15 Plasteel, Advanced component 4 Advanced components, 26,000 ticks (7.22 mins) of work, and a Crafting skill of 8.


A circadian half-cycler is installed in the brain and removes the Sleep need entirely. Consciousness is reduced by 15%, which itself reduces work-related stats like Moving and Manipulation, as well as Eating and Talking.

When a pawn with this implant is shocked with EMP, they will receive brain shock, knocking them unconscious temporarily.


Installing the part requires 2,500 ticks (41.67 secs) of work, 2x medicine of herbal quality or better, and a Medical skill of 5.

Removing the part requires 2,500 ticks (41.67 secs) of work, 1x medicine of herbal quality or better, and a Medical skill of 5.

If the operation fails, the part will be destroyed.


Assuming a colonist sleeps for 8 hours, this implant allows them to work an additional 1/3rd of the day, and saves space on a bedroom. Even with the consciousness loss, this makes pawns have more work time, and thus better for many tasks. This assumes you don't have many sleep reducers; see #Comparison to reducing sleep for details on that.

An unfortunate side effect of the half-cycler is mood. No sleep will prevent Lovin' entirely, remove the moodlet from an impressive bedroom, and deprive a pawn of a bed's Comfort level. An armchair can provide comfort for crafter-type pawns, but all these mood-increasers are quite significant. Non-ascetic nobles still desire a bedroom that meets their needs. Also, remember that darkness will reduce work speed, even with a half-cycler, so you'll want to install lights around your base.


The Consciousness loss has a different effect on different work types.

  • Research, Hauling, Cleaning: All these tasks are done slower, but have no quality, so the extra time makes up.
  • Cooking: Like above; food poisoning chance is not increased.
  • Construction, Crafting, Art: will produce the same-quality items, so the extra time is a net positive. Note that low-skill construction is more likely to fail.


  • Plants: Allows more plants to be grown/harvested, but lowers yield per plant. Bad when plant space is limited, good if not.
  • Mining: Good for mining regular rock or deep drilling, bad for mining ores.


  • Social, Animals: The half-cycler is of little help: trade is limited, prisoners and animals sleep. Lowered Consciousness means more failed attempts and higher prices.
  • Medical: Tends slower, with less quality, and have less successful surgeries. Tend speed is time-sensitive; speed is important, but you don't need to tend all the time.
  • Combat: Worse accuracy, will get injured more, and more likely to die from Consciousness loss. Being tired does not penalize combat, so the half-cycler is a pure negative.
    • EMP also becomes harder to use due to Brain Shock. You may want to use EMP anyway, and if it hits the half-cycler pawn, they'll be stuck downed.

Of course, pawns can be good at multiple work tasks. A pawn that mostly does Crafting can also be your main Social pawn, for instance. Each case should be weighed individually.

Synergy with GenesContent added by the Biotech DLC[edit]

Since the half-cycler removes the need for sleep, making any effect on Sleep Fall Rate irrelevant, it synergizes well with the Sleepy and Very Sleepy genes. Both become essentially free negative genes, providing +2 and +4 metabolic efficiency respectively. This is perhaps not enough to make the whole implant worth it alone, but on any pawn who already has a half-cycler, this is a large, completely free, secondary benefit.


Comparison to reducing sleep[edit]

Other than quick sleeper, the following can decrease the time needed to sleep:

And, of course, the circadian assistant.

The following combinations warrant comparison:

Amazing Beds + Assistant: In total, a masterwork bed + assistant reduce sleep to 5.04 hours - that's 21% of the day. A legendary royal bed + assistant reduces sleep to 3.96 hours (16.4% of the day). If you can easily create Masterwork/Legendary beds, such as with a Production SpecialistContent added by the Ideology DLC, then the half-cycler can end up a negative to work compared to a circadian assistant.

Excellent Beds + Sleep AcceleratorContent added by the Ideology DLC: An excellent bed + sleep accelerator reduces sleep to 5.1 hours (21.2% of the day). A legendary royal bed + accelerator reduces sleep to 3.75 hours (15.6% of the day). Note that the accelerator does cost a fair bit of hunger and power, and is only available if you have a pawn with a Transhumanist ideoligion.

Just Low SleepContent added by the Biotech DLC: On a normal bed, low sleep alone reduces sleep to 3.43 hours (14.26% of the day). As the half-cycler reduces practically all work by -15%, this gene is a flat out improvement. The gene comes at the cost of -4 Metabolic Efficiency, which must either be compensated with bad genes, or increase hunger by up to x200%. Sanguophages already come with Low Sleep - installing a half-cycler is a net negative to them.

In all 3 cases, the pawn can still receive a bed's comfort, Lovin', and the Impressive Bedroom moodlets. These scenarios can be further improved with any of the other methods listed above. However, they'll have to walk to and from the bedroom/barracks, which is a minor time loss.

Comparison to Never SleepContent added by the Biotech DLC[edit]

The never sleep gene will completely prevent sleep with no Consciousness loss. However, with a metabolic efficiency of -6, it requires negative genes or archite metabolism to even be used at all. It takes a large amount of negatives to negate the penalty, or 2 archite capsules for the aforementioned metabolism gene.

Never sleep is not found in any of the default xenohumans, so a genepack must be found/bought. You must also obtain a genepack to compensate for metabolism. Alternatively, you can start with a xenotype with the gene - this still comes at the genetic cost.