Glycine

With peptides

Glycine pairs naturally with the Russian-origin sleep and cognitive peptide cluster. DSIP (delta sleep-inducing peptide) operates directly on slow-wave sleep architecture — peptide-level intervention at a different layer than glycine's body-temperature mechanism. Selank (a tuftsin analog) provides anxiolytic effects via GABA modulation — useful when sleep is blocked by anxious arousal rather than circadian or thermal issues. Glycine handles the sleep-onset thermoregulation and inhibitory neurotransmission arms. Mechanistically complementary, no known negative interactions. Introduce one variable at a time when starting a new stack so you can tell what's actually doing what.

With supplements

1. Magnesium glycinate — GABAergic and neuromuscular relaxation. The glycinate form already contains some glycine but at sub-RCT doses; stack the full 3 g glycine separately.
2. Melatonin — circadian signal (low-dose 0.3–0.5 mg). Different mechanism, fully compatible. Glycine helps you fall asleep; melatonin tells the body it's the right time to.
3. Apigenin — GABA-A positive allosteric modulator. Complements glycine's inhibitory-neurotransmitter arm; both target sleep onset but via different receptor families.
4. L-Theanine — alpha-wave relaxation. Useful pre-bed for users with mental chatter; complements the thermoregulation arm.
5. Tart cherry — endogenous melatonin precursor profile plus anti-inflammatory effects on sleep. Compatible chronic-use pairing.

With lifestyle

1. Warm shower/bath 60–90 min pre-bed. Same thermoregulation logic as glycine — the post-bath cool-down accelerates the core-temperature drop. Stacks naturally.
2. Cool bedroom (~65–68°F / 18–20°C). Supports the heat-shedding step glycine facilitates. Hot bedrooms blunt glycine's mechanism.
3. Consistent sleep schedule. Glycine works on top of circadian alignment, not as a substitute. Variable bedtimes erode the body-temperature curve glycine is designed to ride.
4. Partial sleep restriction buffering. Bannai 2012 specifically documented glycine's benefit on next-day function after curtailed sleep — useful for known short-sleep nights (travel, shift work, parenting).

Common (mostly transient)

1. Mild GI discomfort — soft stools or mild nausea at higher doses (5 g+). Resolves with dose reduction.
2. Drowsiness if dosed too early — the body-temperature drop produces mild somnolence. Don't take 3 g and then drive.
3. Sweet aftertaste — glycine is faintly sweet; some users find it pleasant, others mildly off-putting.

Less common (watch-list)

1. Vivid dreams — occasionally reported, likely tied to preserved or extended REM during the cooling phase.
2. No documented serious adverse events at standard 3 g dose across the published RCT base.

Drug and supplement interactions

1. Clozapine (antipsychotic). Avoid supplemental glycine — glycine can interfere with clozapine's efficacy via NMDA-receptor mechanisms. This is the one well-documented contraindication.
2. Other antipsychotics — theoretical NMDA interaction concern. Coordinate with prescribing clinician if on chronic antipsychotic therapy.
3. Sedatives (benzodiazepines, Z-drugs, antihistamines) — additive mild sedation possible. Not a contraindication but watch total sedation load on first use.
4. Other sleep supplements — generally compatible (see Stacks section). The only conflict is over-dosing total inhibitory tone if multiple GABAergic + glycinergic agents are stacked aggressively.
5. Pregnancy — limited data; consult clinician. Glycine is endogenous and food-abundant but supraphysiological supplemental doses in pregnancy aren't well-characterized.

How much glycine should I take for sleep?

3 grams (3,000 mg), 30–60 minutes before bed. This is the dose used in every major human RCT (Inagawa 2006, Yamadera 2007, Bannai 2012). Higher doses (6 g, 9 g) have been tested in safety studies with no concerning signal but no clear additional sleep benefit. Lower doses (1–2 g) are not well-characterized in sleep trials — they may work for some users but you're below the RCT-validated range.

Will glycine make me groggy in the morning?

Generally no — and that's the most distinguishing feature of glycine versus other sleep aids. The Bannai 2012 follow-up trial specifically measured next-day fatigue and psychomotor vigilance after partial sleep restriction; the glycine group showed reduced fatigue and better PVT performance versus placebo. The body-temperature mechanism (rather than receptor-level sedation) is the likely reason — glycine helps you fall asleep faster and sleep more efficiently without the next-morning sedation tail of antihistamines or benzodiazepines.

How long until glycine starts working?

Most users report changes within the first 2–3 nights of consistent use. The published RCTs measured effects within the first week. Glycine isn't a habit-builder like melatonin in that sense — the body-temperature effect operates the night you take it. If you've taken 3 g pre-bed for 7–10 nights and notice nothing, glycine probably isn't your sleep lever. Don't keep pushing the dose higher in hope of an effect that didn't emerge at the RCT dose.

Can I take glycine with melatonin or magnesium glycinate?

Yes — they target different layers of sleep biology. Melatonin is a circadian signal (when to sleep); magnesium glycinate is GABAergic and neuromuscular relaxation; glycine is body-temperature regulation and inhibitory neurotransmission. No known interactions between the three. Worth knowing: magnesium glycinate already contains some glycine, but a typical 200 mg magnesium glycinate dose provides only ~1 g of glycine — well below the 3 g sleep dose. If you stack them, you still want the full 3 g glycine pre-bed.

Can I stack glycine with DSIP or Selank?

Yes — the stack is mechanistically natural and addresses different layers of sleep and recovery. DSIP (delta sleep-inducing peptide) modulates slow-wave sleep architecture directly — peptide-level intervention on sleep depth. Selank is a tuftsin analog with anxiolytic effects via GABA modulation — useful when sleep is blocked by anxious arousal rather than circadian or thermal issues. Glycine handles the body-temperature drop and sleep-onset latency arm — RCT-validated in healthy adults with mild sleep complaints. Different mechanisms, mechanistically compatible. No known negative interactions.

Will glycine help with diagnosed insomnia or just mild sleep issues?

The honest answer: the RCT base is in healthy adults with mild-to-moderate sleep complaints, not diagnosed primary insomnia or chronic insomnia disorder. Sample sizes were small (10–20 subjects per trial), durations were short (single night to a few weeks), and severity was mild. Whether glycine moves the needle in clinical insomnia is genuinely unknown — it might, but the evidence doesn't establish that case. For chronic insomnia, CBT-I is the first-line intervention with the strongest evidence; glycine is reasonable as an adjunct but not a substitute.

Does glycine come from animal sources? Is it vegan?

Most commercial supplemental glycine is produced via industrial fermentation or chemical synthesis — vegan-suitable regardless of supplier in nearly all cases. Glycine is also naturally abundant in collagen-rich foods (bone broth, skin, gelatin, connective tissue), which is why traditional cooking with bone broth provides a meaningful glycine dose. If you're vegan and want food-source glycine, it's harder to get — beans, lentils, sesame seeds, and pumpkin seeds are the better plant sources but provide far less per serving than animal collagen.

Powder vs capsules — which is better?

Powder, almost always. Glycine has a faintly sweet taste that's pleasant in water, and a 3 g serving is roughly a level teaspoon — easy to measure. To get 3 g from capsules you need 4–6 large capsules (most are 500 mg), which is annoying to swallow nightly. Powder is also significantly cheaper per gram. The exception is travel or shared bathroom storage where a sealed capsule bottle is more practical than a powder tub.