← LearningLibrary · deliberately not sponsored

Shelves, explained76 kinds of product

What each thing on the sleep, fitness, body, therapies and personal-care shelves actually does, how sure anyone can be, what to look for when you buy one, and who should be careful. “No real evidence” is an answer this library gives often, on purpose.

Moderate or better27of 76

Studies cited203

SleepOpen the shelf →

BlanketsA layer you add or remove to fine-tune warmth. Comfort and washability are the point; no blanket has health benefits.none60 Duvet CoversA washable shell for your duvet. Choose by fabric, fit and closure; there are no health claims to weigh.none60 Duvets & ComfortersHow warm a duvet is depends on the amount and type of fill, not the label. Pick the warmth for your room and a build you can wash, and ignore 'hypoallergenic'.none60 MattressesThe one bed purchase with a real trial behind it: for back pain, medium-firm beat firm. Beyond that, choose by fit to your body and sleep position, and a fair trial.limited60 Pillow Protectors & CasesProtectors keep sweat and stains out of pillows; cases are about feel. Neither treats allergies, and silk's skin and hair claims are untested.none60 PillowsSurprisingly little evidence on shape or fill. Match the height to your sleep position so your neck stays level, and judge by how your neck feels in the morning.limited60 SheetsSheets are about feel and heat. Weave and fibre matter more than thread count, and no sheet has health benefits, though a breathable one helps hot sleepers.none60 Bed FramesA frame just has to support the mattress properly. The one feature with health evidence is raising the head of the bed, which helps night-time reflux.limited58 Mattress ProtectorsWorth having to keep sweat and spills out and protect your warranty. They don't treat allergies, and waterproof layers can sleep warmer.none40 Sleep MasksA cheap, low-risk way to make your sleep dark. Most evidence comes from hospital wards, but one home study linked masks to better next-day memory.limited39 Mattress ToppersA 2-4 inch layer that changes how a mattress feels. A cheaper way to soften a too-firm bed; it can't fix a sagging one. No health claims hold up.weak36 Body PillowsLong pillows for side sleepers and pregnancy. No trials test the pillow itself, but going to sleep on your side in late pregnancy is linked with fewer stillbirths.weak27 Bed Wedge PillowsAn inclined foam wedge. Raising your upper body is one of the few reflux measures with trial support; it can't tell you whether your snoring is harmless.limited24 Weighted BlanketsHeavy blankets (usually 3-11 kg / 7-25 lb) filled with glass beads or chain. One good trial helped insomnia in psychiatric patients; overall evidence is limited.limited24 White Noise MachinesSteady sound can mask sudden noises, but the evidence that it improves sleep is very low quality. Keep it quiet, especially near babies.weak24 Sunrise Alarm ClocksA lamp that brightens over half an hour or so before your alarm. Small studies show easier waking, and dawn simulation has trial support for winter depression.limited23 Blackout CurtainsThe simplest route to a dark bedroom. Lab work shows light during sleep affects heart rate and insulin; judge curtains by how well they seal, not the fabric claim.limited22 Blue Light GlassesClear 'computer' lenses do nothing proven for eye strain or sleep. Amber lenses worn before bed have small trials behind them, but dimming the lights does much the same.weak22 Cooling PadsGel and fabric pads feel cool only briefly; water or air systems keep cooling all night. A cool room does most of the work, and pads fine-tune it.limited22 CPAP Machines & AccessoriesCPAP is first-line treatment for obstructive sleep apnea. It is a prescription medical device: get tested first, then mask fit and nightly use decide whether it works.strong22 EarplugsCheap and effective at cutting noise if you insert them properly. The evidence comes mostly from noisy hospital wards; the trade-off is missing alarms.limited22 Heated BlanketsElectric blankets and heated mattress pads warm the bed. No sleep benefit is proven; the real questions are about safety: overheating, burns and fire.none22 Sleep HeadphonesHeadbands and tiny earbuds for audio or noise masking in bed. Music can modestly improve how well you feel you slept; the gear itself is untested. Keep the volume low.limited22 Smart Mattress CoversWater- or air-driven covers that cool or warm the bed, often sold with sleep trackers. Cooling has lab support; trackers are fine for trends but poor at sleep stages.limited22 Smart PillowsFrom contoured neck pillows to anti-snore pillows that inflate to turn your head. The studies are small, and loud snoring needs checking before you buy one.weak22

FitnessOpen the shelf →

Shakers & bottlesShaker cups and bottles are about convenience. Pick one that's easy to clean, doesn't leak, and doesn't hold on to smells.none27 Free weightsDumbbells, kettlebells, barbells and plates: the simplest way to keep adding load in small steps, which is what builds strength and muscle over time.strong19 Core, bodyweight & benchesPull-up bars, dip stations, rings, parallettes, ab wheels, mats and benches: gear that lets your bodyweight, or a dumbbell, do the work.moderate17 Recovery toolsFoam rollers, massage guns and balls, stretch straps, heat and ice wraps, compression boots and vibration plates: small, short-lived effects on soreness and stiffness.limited14 Lifting accessoriesBelts, wrist wraps, straps, hooks, chalk and bar pads: aids for heavy lifting that help performance or comfort a little, but aren't injury insurance.limited13 Cardio & conditioning gearRowers, air bikes, ski machines, jump ropes, battle ropes and plyo boxes: tools for raising cardio fitness, one of the strongest predictors of long life.strong11 Supports & bracesKnee and elbow sleeves, ankle and wrist braces, back supports and compression sleeves. Ankle braces have real evidence; most of the rest is for comfort.moderate11 Resistance bands & suspension trainersElastic bands, tubes, hip circles and suspension straps: cheap, portable resistance that has built strength about as well as weights in the trials so far.moderate8 Training footwearLifting shoes, cross-trainers, running shoes and flat trainers. Choose for comfort and the job; matching shoes to your arch type hasn't prevented injuries in trials.limited7 Gym bags & storageDuffels, backpacks and shoe bags: choose for capacity, a separate section for shoes or wet kit, and a fabric you can wipe or wash.none6

BodyOpen the shelf →

Watch or fitness trackerWrist devices that log heart rate, steps and sleep. Good for resting heart rate and movement; rough for calories, VO₂ max and sleep stages.moderate20 Smart scaleWeighs you accurately and syncs the trend. Its body-fat, muscle and 'metabolic age' numbers are estimates that can be kilograms off for one person.moderate10 Blood pressure monitorThe most useful health device you can own. Buy a model on an independent validated list, in your cuff size, and measure by the standard protocol.strong7 ThermometerFor fever, digital oral or rectal readings are the most reliable; ear and forehead models are faster but miss more fevers. 'Normal' isn't exactly 37°C.moderate4 Smart ringA finger-worn tracker for sleep, resting heart rate, HRV and skin temperature. Fair at sleep timing, shaky on sleep stages; its scores aren't validated.limited1 At-home lab test kitFinger-prick, stool, saliva and swab kits you collect at home and post to a lab. Some are reliable; many panels outrun the evidence, and results need a clinician.limited0 Glucose monitorContinuous sensors and finger-prick meters. Proven to improve glucose control in diabetes; for people without diabetes, little evidence that wearing one helps.moderate0 Heart-rate chest strapAn electrode strap that reads your heart's electrical signal. The reference for heart rate during exercise, and more accurate than any wrist sensor.moderate0 Tape measure and skinfold calipersA tape and one division give your waist-to-height ratio, a better risk flag than BMI. Calipers estimate body fat, but only with practice.moderate0

TherapiesOpen the shelf →

Red light therapyLED panels, masks and caps that shine red and near-infrared light on skin. Modest evidence for hair loss and fine lines; weak for whole-body claims.limited59 SaunaA hot, dry room at 80–100°C. Frequent use is linked to fewer heart deaths in Finnish studies: the best long-term data on this shelf, but observational.moderate57 Cold plungeTubs and chillers for short cold-water dips. Real short-term effects on alertness and soreness, no long-term health data, and bad timing can blunt muscle gains.limited30 Infrared saunaPanels warm your skin directly while the air stays around 45–65°C. Gentler than a Finnish sauna, with a much smaller evidence base of its own.limited24 PEMF deviceMats, pads and coils that pulse a magnetic field into tissue. A few prescription uses exist; evidence for wellness mats is weak, and implants rule them out.weak14 Light therapy boxBright white light for your eyes in the morning. About 10,000 lux for 30 minutes treats winter depression; it's the best-supported device on this shelf.moderate11 CryotherapyChambers that expose you to air at −110°C or colder for 2–3 minutes. The evidence is very low quality, it isn't shown to beat an ice bath, and it has real risks.weak0 Hyperbaric chamberBreathing oxygen under pressure. A proven hospital treatment for specific conditions like decompression sickness; home soft chambers aren't that, and longevity use is unproven.weak0 Pneumatic compressionInflatable boots, sleeves and pumps that squeeze limbs in sequence. Proven medical uses (clots, lymphedema); for sports recovery, mostly a short-term feel-good.limited0

Personal CareOpen the shelf →

MoisturizerDraws water into skin and seals it in. Useful for dry skin and eczema; cheap basic formulas work as well as luxury ones.moderate131 ToothpasteFluoride is the ingredient that matters: decades of trials show fluoride toothpaste prevents decay. Most other claims are secondary.strong86 SerumA light, concentrated delivery vehicle for an active. Worth buying only for an active with evidence, at a disclosed strength.moderate76 ShampooCleans scalp and hair. Anti-dandruff actives have real evidence; 'growth', 'thickening' and 'detox' claims mostly don't.moderate68 SunscreenThe one skincare product with randomized-trial evidence for fewer skin cancers and slower skin aging, if you apply enough of it every day.strong66 Conditioner & leave-inCoats the hair shaft to cut friction, tangles and breakage. A cosmetic job it does well; it cannot repair or grow hair.limited32 Cleanser & soapRemoves dirt, oil and sunscreen. Gentle beats strong for skin; for hands, plain soap and 20 seconds of scrubbing is what prevents infection.moderate31 Hair treatment & maskMasks, bond repair and scalp serums condition damaged hair. For thinning, only minoxidil (and prescription options) has strong trial evidence.moderate27 Styling productCreams, gels and sprays that shape and hold hair. Purely cosmetic; the health questions are heat damage, tight styles and the odd allergen.limited23 MouthwashFluoride rinses help people prone to decay; antiseptic rinses reduce plaque short-term. Neither replaces brushing, and daily antiseptic use has trade-offs.moderate22 Spot & skin treatmentTargeted products for acne, dark marks, rough bumpy skin and eczema patches. A few actives have real evidence; many products are gentle extras.moderate22 Toner & essenceAn optional watery step. Hydrating toners are light moisturizers; acid toners are exfoliants. No toner is needed to 'rebalance' skin.weak19 Fragrance & body mistPure pleasure, no health benefit. The one real health issue is contact allergy, which affects a few percent of people and is usually lifelong.none14 Deodorant & antiperspirantDeodorant masks odor; antiperspirant reduces sweat. The cancer and Alzheimer's scares haven't held up; irritation and fragrance allergy are the real issues.moderate11 Exfoliant & scrubLoosens dead surface cells for smoother, brighter skin. Chemical exfoliants have modest trial evidence; overdoing any exfoliant damages the barrier.moderate11 Face maskA treat, not a treatment. Sheet and sleeping masks hydrate for a while; clay masks absorb oil. No mask has lasting health effects.weak8 Shaving & beard careGels, creams, balms and beard oils reduce friction and irritation. Comfort products with no health claims; technique matters more than the can.weak8 Eye creamA moisturizer in a smaller, pricier jar. Useful if your regular products sting around the eyes; it cannot fix dark circles or bags.weak6 Hand creamA thicker moisturizer for hands that take a beating from washing. Helps prevent chapped, cracked skin and hand eczema, especially if you wash often.limited5 Teeth whiteningPeroxide strips and gels do lighten teeth, at the cost of temporary sensitivity. A cosmetic choice with no health benefit.moderate5 Lip balmSeals moisture into chapped lips. Choose one with SPF for outdoors; lips burn, and sun is the main risk factor for lip cancer.limited4 Floss & interdental cleaningCleans where a toothbrush can't reach. The trials are short and low-certainty, but the habit is cheap, low-risk and targets where gum disease starts.limited3 Intimate care & lubricantPersonal lubricants reduce friction and discomfort. What matters is the base, condom compatibility and osmolality; 'feminine hygiene' washes and douches aren't needed.limited1