You went to bed on time. You are still awake, still running warm, still waiting.
An hour later you are scrolling. In the morning your skin looks tired, a strain from three weeks ago still has not closed up, and the crash after lunch lands on schedule. Nothing here is wrong enough to book an appointment for. Nothing is right, either.
Sleep does not begin in your head. It begins with heat leaving your body: core temperature falls, blood moves out to your hands and feet, and the switch flips. That sequence runs on the smallest amino acid you own — and the combined daily demand from your collagen and your glutathione outruns what your body makes by roughly 10 grams a day. Live in that shortfall long enough and it shows up in four places at once. Shallow sleep. Slower repair. Skin and tendons aging ahead of the rest of you. A harder landing after every meal.
This is a working guide to glycine and GlyNAC — what each does, what it does not do, and how to use them without guessing. Around three grams before bed lowers core temperature and shortens sleep latency, which is why glycine improves sleep quality instead of sedating you into it. The same amino acid is the rate-limiting input your cells use to build glutathione, the antioxidant your mitochondria burn through fastest. It is roughly a third of every collagen strand in your skin, joints and connective tissue, which is why high protein intake alone quietly under-serves collagen synthesis, and why the cofactor layer of vitamin C, zinc and copper matters more than the claim on the tub. Taken before a meal, it blunts the glucose spike that follows, through a mechanism you can test on yourself in two weeks.
Twenty-six chapters, and every one of them ends in something you can actually do.
There is an honest chapter on insomnia: where the line sits between a run of bad nights and a sleep disorder, why CBT-I outranks anything sold in a bottle, and where glycine fits, which is week three rather than week one. There is a ranked comparison of the natural sleep remedies people actually buy — magnesium, melatonin, the rest of the relaxation stack — tested one agent at a time, fourteen days each, scored the same way every night, so you keep only what earns its place.
Then the rest of the work. Collagen peptides against gelatin against bone broth, and what survives digestion. A low-glycemic plate and a ranked glycine-rich foods list. Glutamine, glycine and the gut lining. Tendon and connective tissue under load, for anyone rehabbing an injury that will not close. A four-week GlyNAC ramp for mitochondrial repair. A five-signal screen for spotting glycine deficiency. Separate chapters for women and for men, one for the later decades, and one on using glycine before something breaks rather than after.
Named tools rather than advice: the Bedtime Temperature Switch, the Glucose Spike Dampener Protocol, the Collagen Blueprint Map, the Redox Supply Chain, the GlyNAC Synergy Loop, the Training Fuel Triangle, and the Dose-Response Guardrails. If you are a shift worker fighting daylight for sleep, a lifter whose recovery has stalled, or someone watching their skin change faster than their age should allow, the protocols name you specifically.
The dosing chapter is the one most books skip. Grams and timing, powder against capsules, interactions with medications, the kidney and liver questions people are right to ask, the upper limits nobody prints on the label, and the point at which you stop self-managing and call a professional. A separate chapter sets out what the evidence actually says, including where it is thin.
No miracle framing. No thirty-supplement stack. One inexpensive amino acid, the jobs it genuinely does, and a thirty-day plan that starts with one three-gram dose before bed.
Turn to Chapter 7 and set a timer for tonight.
