Why Sermorelin Should Be Injected at Night
Sermorelin should be injected at night because this timing mimics the natural circadian pattern of growth hormone secretion, which peaks during early sleep, leading to better therapeutic outcomes and physiological effects. 1
Physiological Basis for Nighttime Administration
Growth hormone (GH) in normal subjects displays a consistent circadian variation with a major surge occurring after the onset of sleep, making evening administration of GH-releasing compounds more physiologically appropriate 1
When sermorelin (a growth hormone-releasing hormone analog) is administered at night, it aligns with the body's natural hormonal rhythms, enhancing its effectiveness 2
Evening injections of growth hormone result in significantly greater bioavailability compared to morning injections, with studies showing the area under the curve (AUC) after evening injections (83.3 ± 25.4 μg/L/12h) being almost double that of morning injections (46.0 ± 10.6 μg/L/12h) 1
Clinical Benefits of Nighttime Administration
Nighttime administration of sermorelin produces hormone patterns and metabolite relationships that more closely resemble normal physiological patterns 1
Growth hormone-releasing hormone (GHRH), which sermorelin mimics, has demonstrated sleep-promoting effects in humans, particularly when administered during early sleep periods 3
Evening administration helps maintain proper circadian rhythms of growth hormone secretion, which is important for overall endocrine function 4
Metabolic Advantages
Nighttime sermorelin administration leads to more normalized patterns of lipid intermediates and better relationships between circadian lipid intermediates and blood alanine/lactate concentrations 1
Morning injections of growth hormone-related compounds can disrupt these normal metabolic relationships and lead to increased daytime insulin levels 1
The metabolic effects of subcutaneous GH-related injections are clearly influenced by the timing of administration, with evening injections producing more physiological patterns 1
Practical Considerations
Higher skin and subcutaneous temperatures when in bed at night may contribute to better absorption and bioavailability of sermorelin when injected in the evening 1
Sermorelin is typically administered as a once-daily subcutaneous injection of 30 μg/kg bodyweight at bedtime for treating children with idiopathic growth hormone deficiency, establishing a precedent for nighttime administration 2
Potential Pitfalls and Caveats
While nighttime administration is generally preferred, individual response can vary, and some patients might require personalized dosing schedules based on their specific clinical presentation 2
Transient facial flushing and pain at injection site are the most commonly reported adverse events with sermorelin, regardless of administration timing 2
The sleep-promoting effects of growth hormone-releasing compounds appear to be specific to GHRH (like sermorelin) and not shared by all growth hormone-releasing peptides, as demonstrated by studies with GHRP-2 5