Published studies at 3,000mg glycine show faster onset to deep (slow-wave) sleep and less next-day fatigue. See the research below.
You can't cool your core from the outside.
- ✓ Clinical 3,000mg glycine dose — lowers core body temperature, the switch for deep sleep
- ✓ Cools you from the inside out — the half devices can't reach
- ✓ Melatonin-free — wake up sharp, not groggy
- ✓ Built on the dose used in published sleep research
- ✓ 60-night money-back guarantee
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How inside-out cooling works
To fall into deep sleep, your core temperature has to drop about 1–2°F. Everything you've tried cools you from the outside. The heat is coming from the inside.
You run hot
- Your core isn't shedding heat fast enough
- So your body stays in light sleep
- And you surface at 3am, warm and wired
Glycine flips it
- Acts on NMDA receptors in the brain's sleep-clock
- Opens the blood vessels in hands & feet
- Your body releases heat — core temp falls
Deep sleep holds
- You drop into deep sleep faster
- Fewer middle-of-the-night wake-ups
- You wake up sharp, not groggy
Built on the dose used in published studies
Not a fairy-dusted pinch — the same 3,000mg glycine dose used in peer-reviewed sleep research, in every sachet.
Mechanistic study.
Human PSG study; small sample.
Human study; self-reported measures.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
What happens after you start Cooldown Nightcap
The calm sets in
- L-theanine settles the racing mind
- Easier to drift off
- Some feel the cooldown night one
The 3am soak fades
- Glycine working — core temp drops
- Fewer night sweats
- Waking up less wrecked
The edge holds
- Sleeping through, consistently
- Wake up sharp, not groggy
- Why most start with 60 nights
Why do I wake up hot in the middle of the night? +
To reach and hold deep sleep, your core temperature has to drop. If your body isn't shedding that heat fast enough, you stay in lighter sleep and surface — often warm and wide awake. Glycine supports that core-temperature drop from the inside.
Is it just melatonin? +
No — melatonin-free by design. Melatonin only shifts when you feel sleepy. It does nothing about the heat. Glycine works on temperature — a different mechanism.
Why 3,000mg of glycine? +
That's the dose used in the published sleep studies (Kawai 2015, Yamadera 2007, Bannai 2012). Most sleep products skip glycine or under-dose it. Every sachet delivers the full 3,000mg.
Will it leave me groggy? +
It works by improving the quality of your sleep, not by sedating you — so the research points the other way: less next-day fatigue and better clear-headedness. Melatonin-free, non-habit-forming.
What if it doesn't work? +
60 nights, money back, keep the box. One refund per customer.
Independent reports from long-term glycine users (not Cooldown Nightcap customers). Your own verified reviews drop in here as they come in.
Whole-night sleep
"My insomnia is waking in the middle of the night and struggling to get back… Started glycine 2 months ago and finally slept through — it feels like whole-night sleep, and I feel much better."
4am used to own me
"Added glycine to my sleep stack — absolute game changer. 4am is a time of day I detest. Now I sleep deeply through the night and wake more refreshed than I did on CBD."
My Oura proved it
"Tracked it on my Oura. Made a large difference in sleep quality. Removed it — quality dropped. Re-added — it jumped back. This is a permanent supplement for me."
Functional the next day
"Prescription sleep aids helped but I wasn't functional the next day. Glycine keeps me in a deeper state so my mind stays in the 'off' mode — slept through the night."
5 ingredients in 1 cooldown formula
Most sleep supplements skip the dose that matters. Cooldown Nightcap uses the full 3,000mg clinical dose of glycine — the amino acid studied to lower core body temperature — plus the exact stack men already hand-build one bottle at a time, dosed right. Melatonin-free. Stop hand-stacking.
Cool your body from the inside out
— and finally sleep through the night
Cool the room. Then cool you.
Cooling your bedroom helps — but it can't reach your core. That's the half glycine handles, on its own or alongside whatever you already use.
Changes timing
- Doesn't cool anything
- Ignores the heat waking you
- Often groggy the next day
Room · sheets · mattress
- Cools the surface around you
- Genuinely helps — keep it
- But it can't lower your core
Cools you — from the inside
- Glycine lowers core temperature
- The half devices can't reach
- Works solo, or with your setup
What glycine users report
Real reports from long-term glycine users (not Cooldown Nightcap customers). We'll replace these with your own verified reviews as they come in.
Whole-night sleep
"Started glycine 2 months ago and finally was able to sleep through — although my monitor still shows wake events, it feels like whole-night sleep, and I feel much better."
Game changer
"Added glycine to my sleep stack — absolute game changer. 4am is a time of day I detest. Now I sleep deeply through the night and wake more refreshed than I did on CBD."
My Oura proved it
"Tracked it on my Oura. Big difference in sleep quality. Removed it and quality dropped; re-added and it jumped back. Permanent supplement for me."
Stops the 4-hour wake
"Usually wake after about 4 hours and can't get back to sleep. Started glycine a week ago and it's amazing — completely stops that from happening."
