Poor sleep as a quiet epidemic: why night-time recovery matters
You know the feeling: a long day, high stress, and sleep either will not come or will not settle. Yet enough good-quality sleep is not a luxury but the foundation of your health. It is when your brain tidies up and your body repairs itself. So what does collagen have to do with it? The answer leads to an amino acid that is especially common in collagen.
The invisible work sleep does for body and mind
Good sleep is not just a pause; it is an active repair process.
The role of deep sleep (SWS) and REM sleep
Deep sleep (slow-wave sleep, SWS) and growth hormone release are linked: in data from 149 healthy men, the amount of growth hormone secreted was significantly associated with slow-wave sleep, independently of age.[1] REM sleep (rapid eye movement), by contrast, is crucial for consolidating memory and processing emotion. Any disruption to these phases costs you the next day.
What chronically poor sleep does
Chronically poor sleep goes well beyond tiredness. Laboratory and population studies have linked short sleep with changes in metabolism, poorer results in performance tests and a higher cardiovascular risk.[2] This is where the amino acid glycine comes in.
Glycine: the most common amino acid in collagen
Most people know collagen as the structural protein in skin and joints. Its largest component is the amino acid glycine, roughly 30% of all collagen. Glycine is described in the nervous system as an inhibitory neurotransmitter and has been examined in sleep studies.
Glycine as an inhibitory neurotransmitter
Unlike excitatory neurotransmitters such as glutamate, glycine dampens the passing on of nerve signals.
A direct effect on the central nervous system
In the spinal cord and parts of the brain, glycine acts as an inhibitory neurotransmitter.[3] It binds to specific receptors and slows neuronal activity. Think of glycine in the nervous system as a kind of brake that dampens signals.
Lowering core body temperature
In experiments in rats, orally administered glycine lowered core body temperature.[4] Studies show that taking glycine orally raises skin temperature, particularly in the hands and feet, which draws heat from the core out to the periphery. A slight drop in core temperature is an essential signal for the body to shift into sleep mode.
Collagen as a source of glycine
Glycine occurs in many proteins, but collagen is among the richest dietary sources of it.
High concentration and bioavailability
Hydrolysed collagen is a simple way to take in a larger amount of glycine. After gelatin hydrolysate was taken, the peptide form of hydroxyproline in the blood of healthy volunteers rose and peaked after 1–2 hours.[5]
You have seen that around 30% of collagen is glycine. Hydrolysed collagen supplies this glycine in the form of small peptides. The collagen powder from the Kollagen Institut is free of unnecessary additives and fits easily into your evening routine.
What studies on glycine and sleep measured
Studies on glycine before bed
Several studies have looked at taking glycine before bed.
Time to fall asleep and night-time waking
In a randomised crossover study, people with complaints about their sleep quality took 3 g of glycine or a placebo before bed; their state the next morning was recorded with questionnaires.[6] You fall asleep faster and stay settled longer.
Sleep efficiency and how rested people felt
Particularly relevant: the studies also measured sleep efficiency, the proportion of time in bed actually spent asleep. In a study of healthy volunteers whose sleep was cut by 25% for three nights, participants given 3 g of glycine before bed reported significantly less fatigue the following day.[7] In other words, sleep quality improves even when total sleep duration changes only slightly.
Choose a collagen with a demonstrably low molecular weight. The peptides in the products from the Kollagen Institut are hydrolysed, meaning split into small fragments.
Glycine and next-day cognitive performance
Some studies also recorded how participants felt and performed in tests on the day after intake.
Daytime fatigue
In people with ongoing complaints about their sleep quality, lower fatigue scores were recorded the next morning after 3 g of glycine before bed.[8] This suggests glycine optimises sleep quality enough that the restorative effects are used well even when duration is not ideal.
Memory and attention
One study also recorded memory recognition tasks during the day after participants took 3 g of glycine before bedtime.[9] This is attributed to better-quality deep sleep and improved recovery of the central nervous system.
Glycine and overnight repair processes
Glycine is also a building block your body uses for its own proteins, collagen among them.
Glycine as a building block for protein synthesis
Night is the main window for tissue repair.
Collagen synthesis during rest
Your body's own collagen synthesis is an energy-intensive process that runs mainly during rest. Collagen peptides are rich in glycine and proline.
Glycine and creatine synthesis
Together with arginine and methionine, glycine is one of the three building blocks from which the body makes creatine.[10]
Glycine, glutathione and metabolism
Glycine is used in metabolism to build several of the body's own molecules, among them glutathione and creatine.
Buffering oxidative stress
Glycine is one of the three amino acids from which the body makes glutathione, a key antioxidant of its own.[11] Glutathione production runs continuously to clear cellular debris and oxidative stress. Supplying it through collagen supports that overnight detoxification and the repair of cell structures.
Protein and blood sugar
In 2002, Gannon et al. recorded the blood sugar response of nine healthy people to 25 g of glucose taken together with glycine.[12] Sleep was not an endpoint in that study.
How and when to take it
If you want to take collagen in the evening, here are a few practical pointers.
Taking collagen in the evening
Timing and dose
Most of the successful sleep studies used a dose of 3 g of glycine.[6] Collagen is roughly one third glycine, so 10 g of collagen powder contains about 3 g of glycine – whether that acts like isolated glycine is an open question. If you take collagen in the evening, 30 to 60 minutes before bed works well.
Choosing the product
Always choose hydrolysed collagen with a low molecular weight (< 2,000 daltons). Look for high purity too, tested for heavy metals and additives.
What else helps overnight recovery
Good sleep hygiene still matters most.
Magnesium and L-theanine
Magnesium has also been studied in relation to sleep: a trial in 46 older adults recorded sleep-onset time and sleep efficiency, among other measures, after eight weeks of 500 mg magnesium daily.[13] L-theanine, from green tea, promotes alpha waves in the brain, supporting a state of alert relaxation.
Getting your sleep environment right
No supplement can make up for poor sleep hygiene. Keep the room cool and dark, below 18 °C, and reduce exposure to blue light from screens for at least an hour before bed.
With supplements, quality is worth a close look. Look for verified purity. That is exactly what we care about at the Kollagen Institut.
Conclusion
What links collagen and sleep is mainly one amino acid: glycine. Studies have examined doses of around 3 g of glycine before bed, recording sleep onset time, sleep efficiency and morning questionnaires. Collagen powder is a glycine-rich protein source.
If you take collagen, choose a pure, hydrolysed one.