Why cycles exist
Cycling — running a compound for a defined period, then stopping — is a convention that arrived from two directions. The first is receptor desensitisation: sustained stimulation of a receptor often reduces the response to it over time, which is well characterised in pharmacology generally. The second is practical: an intermittent structure gives you data points. You learn what a compound does, and what stopping it does, which continuous use never tells you.
Not every compound needs cycling. GLP-1 agonists, for example, are used continuously under medical supervision by design, because their effects reverse when stopped and because that is how the clinical trials were run.
The standard shapes
- Continuous: ongoing use, appropriate where the intervention corrects a deficit rather than amplifying a signal.
- Fixed-length cycle: a defined period followed by a break — the dominant pattern for GH secretagogues.
- Pulsed: short bursts with short breaks, commonly used for telomerase-directed compounds.
- Loading then maintenance: a more intensive opening phase followed by a reduced upkeep frequency — the usual structure for TB-500.
Timing is not a detail
For GH secretagogues, timing within the day materially changes the response. Growth-hormone release is naturally pulsatile, with the largest pulse occurring in deep sleep. Two practical consequences follow:
- Dosing before sleep aligns the exogenous pulse with the natural one, rather than competing with it.
- Dosing near food blunts it. Circulating glucose and insulin suppress growth-hormone release, so the standard guidance to dose on an empty stomach reflects a real physiological effect rather than protocol folklore.
For cognitive peptides, timing follows the desired effect: Semax in the morning and early afternoon, not late in the day, because it is activating and can disturb sleep. Selank sits comfortably in the evening.
Planning a washout
A washout is the deliberate gap after a cycle. Its length should be proportionate to how long the compound was used and how long its effects persist.
As a rough convention in practice:
- Compounds used for four weeks get a break of at least equal length.
- Compounds used for eight to sixteen weeks get a break of four weeks or more.
- Compounds with very long half-lives or sustained effects need longer, because the compound itself is still present for part of the gap.
There is no evidence-based formula here. The principle is simply that the break should be long enough to observe your baseline again — because that is the only way to know whether the compound was doing anything.
Monitoring during a cycle
If a protocol is worth running, it is worth measuring. What you measure depends on the compound:
- GH secretagogues: fasting glucose and, where possible, IGF-1. Rising glucose is the most relevant early signal.
- Metabolic compounds: weight trend, food intake, and a clinician's input on labs.
- Repair peptides: a functional measure — pain score, range of motion, a specific movement you can repeat.
- Cognitive compounds: something scored, not remembered. Sleep quality and subjective recall are notoriously unreliable over weeks.
A measurable endpoint is what separates a protocol from a habit.
Stop rules worth writing down in advance
Decide before you start what would make you stop. Not afterwards, when the answer is influenced by not wanting to have wasted the money. Common stop rules:
- Any new prescription medication, until a clinician has reviewed the combination.
- Persistent side effects that do not resolve within a few days of onset.
- Fasting glucose drifting upward on consecutive readings.
- Any injury or illness that changes the risk calculus — particularly anything with a proliferative or vascular component.
The bottom line
Cycle structure is the least evidenced and most practically important part of this field. Nobody has run a trial comparing eight weeks to twelve, or four weeks of washout to eight. What the structure does is make an intervention observable, which is why the convention has survived despite the absence of data.