You can hit every set, eat every meal and still wreck your progress if you spend the night surfacing from sleep. Fragmented sleep is the hidden leak in many lifters' recovery. A small 2024 trial in European Journal of Nutrition suggests that a scoop of collagen peptides before bed might patch it. The result is interesting, but it comes with caveats you should know before you buy a tub.
Why Collagen at Bedtime? It's the Glycine
Collagen is unusually rich in glycine, an amino acid that makes up roughly one in three of its amino acid residues. Most protein powders contain far less. Glycine has long been studied as a sleep aid, and earlier small trials using around 3 g before bed reported better subjective sleep quality. Collagen peptides are a cheaper, more familiar way for lifters to get glycine, alongside other amino acids.
The researchers, from Loughborough University and collaborators, wanted to know whether a glycine-rich collagen peptide supplement could improve sleep in physically active men who already had sleep complaints.
The Study: What Was Actually Done
The design was strong for a small trial:
- Participants: 13 athletic men, average age 24, training about 7 hours per week
- Sleep problems: an average Athens Insomnia Scale score of 9, indicating real sleep complaints
- Intervention: 15 g of collagen peptides or a placebo, taken 1 hour before bedtime for 7 nights
- Format: randomized crossover, so each man did both conditions, with at least 7 days between trials and a 7-night familiarisation period beforehand
- Measurements: sleep diaries and actigraphy for all 7 nights, plus polysomnography (the lab gold standard) and core temperature on night 7. Cognition, inflammation and hormones were assessed that night and the next morning.
The crossover format matters because each athlete served as his own control, which reduces noise in a tiny sample.
What Improved: Fewer Awakenings and a Sharper Morning
Fewer awakenings. Polysomnography recorded 21.3 ± 9.7 awakenings with collagen versus 29.3 ± 13.8 with placebo (P = 0.028). That is 8 fewer wake-ups per night, about a 27% reduction.
The diaries pointed the same way. Over the 7 days, self-reported awakenings averaged 1.3 ± 1.5 with collagen versus 1.9 ± 0.6 with placebo (P = 0.023). Objective and subjective measures agreeing is a good sign.
Better morning Stroop accuracy. The morning after night 7, participants answered a higher proportion of baseline Stroop trials correctly with collagen (1.00 ± 0.00) than with placebo (0.97 ± 0.05; P = 0.009). The Stroop test measures attention and the ability to override automatic responses. A perfect score against 0.97 is a small gap, and it hints at a possible ceiling effect. It is encouraging but not proof of a big mental edge.
What Didn't Improve: The Reality Check
This is where the clickbait ends. Collagen did not change:
- Total sleep time
- Sleep latency (how fast you fall asleep)
- Sleep efficiency
- Core temperature
- Hormones or inflammatory markers
- Subjective sleepiness, fatigue or overall sleep quality
- Other cognitive tests
So collagen is not a sedative, and it didn't help people drift off faster or sleep longer. The one thing that moved was how often sleep was interrupted. If your problem is lying awake for an hour, this study offers little for you.
Limitations You Should Know About
- Tiny sample: 13 men. Small trials often overestimate effects and can't show whether results apply to women, older adults or non-athletes.
- Short duration: 7 nights. We don't know whether the benefit lasts, grows or fades.
- Single-night lab data: polysomnography was recorded only on night 7, so the headline awakenings figure comes from one night per condition.
- Industry-supplied product: the supplement was supplied by Rousselot, and two authors are employees of the company. That doesn't invalidate the work, but independent replication would carry more weight.
- Many outcomes: a lot of measures were tested, and only a few reached significance, so some findings could be chance.
How to Use This: Practical Takeaways
The protocol studied: 15 g of collagen peptides, about 1 hour before bed.
Who it might suit: athletes and lifters who sleep poorly because of frequent awakenings, not those who struggle to fall asleep. If you track your sleep and see many mid-night wake-ups, a 1–2 week self-experiment is low-risk. Keep everything else constant, and judge it by how many times you wake and how you feel in the morning.
Collagen vs. 3 g glycine: Pure glycine at around 3 g is the more studied sleep-specific option, and it's cheap and compact. Collagen offers glycine plus other amino acids and fits easily into a nightly shake, but you need a much larger dose, and the evidence for it is thinner. Collagen is not a complete protein, so it shouldn't replace your main protein sources. Treat it as an add-on, not a swap. If you want the simplest, best-evidenced route to glycine, plain glycine is reasonable. If you already use collagen, the 15 g bedtime serving is a logical test.
The Bottom Line
A 27% drop in night-time awakenings is a real, measurable result, but it comes from 13 men over one week with an industry-supplied product. Collagen peptides before bed look like a promising, low-risk experiment for lifters with fragmented sleep, not a proven cure. Try it, track it honestly, and keep the fundamentals in place: consistent bedtimes, a cool dark room, and caffeine cut-offs.
Source: Thomas C, et al. Eur J Nutr. 2024;63(1):323-335. doi: 10.1007/s00394-023-03267-w.
