Mattress Glossary

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A motorized bed base that allows independent angle adjustment of the head and foot of the mattress. Requires a compatible mattress (usually foam or pocketed-coil hybrid). Popular for couples with different positions, back pain relief, snoring reduction, and general comfort. Also called a split base in Split King configurations.

Nolah's proprietary graphite-infused comfort foam. Nolah claims independent pressure-map testing shows AirFoam™ outperforms memory foam in peak pressure reduction. The graphite infusion improves thermal conductivity vs. standard memory foam.

The traditional hourglass-shaped coil connected to others via helical wire. The oldest coil type (patented 1865), cheap to produce, and provides a bouncy traditional innerspring feel. Less motion isolation than pocketed coils due to the interconnected structure.

A permanent indentation in the mattress surface from consistent body weight over time. Impressions under 1 inch are normal and expected. Most warranties cover impressions greater than 1–1.5 inches. Memory foam is more prone to premature impressions; latex and coils resist longer.

A mattress's immediate responsiveness and tendency to push back against compression. High bounce (latex, coils) allows easy position changes and active use. Low bounce (memory foam) cradles but makes movement more effortful. Couples often prefer moderate bounce for ease of movement.

A mattress compressed, rolled, and shipped in a box via standard parcel carriers (FedEx, UPS, or freight). The innovation that enabled the DTC mattress revolution. Only foam, latex, and certain hybrid mattresses can be compressed; traditional innerspring cannot.

A wooden frame with springs covered in fabric, used under mattresses for support and height. Traditional innerspring mattresses were designed to work with box springs. Modern foam and hybrid mattresses do not require and often should not use box springs — a solid foundation or platform is required.

Amerisleep's plant-based memory foam replacing a portion of petroleum-based ingredients with plant-derived oils. More breathable and responsive than traditional memory foam while retaining pressure-relieving properties. CertiPUR-US® certified.

Foam (typically memory foam) with copper particles added. Copper is thermally conductive (dissipates heat) and naturally antimicrobial. Used by brands like Layla and Nectar Premier Copper as a cooling and hygiene enhancement.

A proprietary fiber blend by Hologenix containing thermo-reactive minerals (titanium dioxide, silicon dioxide, etc.). When woven into fabric, it absorbs body heat and re-emits it as far-infrared energy. The FDA has determined Celliant® is a general wellness technology that may support local blood circulation.

The number of coils in a mattress for a given size. For a queen: 400–600 is standard, 600–800 is good, 800+ is premium. Higher count doesn't always mean better quality — coil gauge and tempering matter equally. Coil count alone is often used as a misleading marketing figure.

The thickness of the wire used in coils, measured in gauge numbers. Counterintuitively, lower gauge = thicker wire = firmer coil. 12–14 gauge is firm; 14–16 gauge is standard; 16–18 gauge is softer. Heavier sleepers benefit from lower-gauge (thicker) wire for durability.

The top layer(s) of a mattress responsible for pressure relief, feel, and initial comfort. Typically 2–4 inches in standard mattresses, up to 6+ inches in plush or luxury models. Materials include memory foam, latex, gel foam, and fiber.

A mattress's ability to dissipate body heat and maintain a comfortable sleeping temperature. Affected by construction (hybrid > latex > foam), cover material (PCM vs. standard), and foam additives (gel, graphite, copper). A key purchasing factor for the ~25% of adults who report sleeping hot.

A voluntary certification for polyurethane foam ensuring it's made without ozone-depleting chemicals, heavy metals, formaldehyde, phthalates, and flame retardants like PBDEs and TCEPs, and has low VOC emissions. The baseline foam safety certification in the US. Does not certify organic status.

The internal 24-hour biological clock regulating sleep-wake cycles, hormone release, and body temperature. Core body temperature naturally drops 1–2°F at sleep onset, which is why cool sleeping environments and temperature-neutral mattresses support faster sleep onset and deeper sleep.

A latex processing method where liquid latex is poured into a mold, baked, and set. The natural settling creates a slightly denser bottom layer. Generally firmer, more supportive, and more durable than Talalay. Commonly used in support cores.

A retail model where brands sell directly to customers online, bypassing traditional retail intermediaries. The DTC model significantly reduces markup on mattresses. Casper and Tuft & Needle pioneered mattress DTC in 2014; now virtually all major brands have an online channel.

N3 (slow-wave) sleep — the most physically restorative sleep stage. Growth hormone release, immune function, tissue repair, and memory consolidation occur during deep sleep. Mattress pressure points and temperature discomfort reduce deep sleep time by triggering micro-arousals.

Sleep Number's proprietary air chamber system. Two independent air chambers allow per-side firmness adjustment from 0–100. The foundation of all Sleep Number mattresses. Modern versions include automatic firmness adjustment based on biometric tracking.

A comfort layer stitched flush with the mattress cover, creating a flat-top appearance. Provides a more uniform feel than a pillow top and tends to resist shifting over time. Common in luxury mattresses from Saatva, DreamCloud, and WinkBed.

How well a mattress maintains its structure and supportiveness at the edges when weight is applied near the perimeter. Poor edge support creates a 'roll-off' feeling and reduces usable sleep surface. Reinforced perimeter coils and high-density foam edges improve edge support.

The weight in pounds per cubic foot (lb/ft³) of foam. Higher density = more material = more durable and supportive. Comfort foam: 3–5 lb/ft³ for memory foam is good; support foam: 1.8+ lb/ft³ is a quality baseline. Not to be confused with firmness.

A dual-sided mattress designed to be slept on from either side, with each side offering a usable sleep surface (often different firmness levels). Rare in modern mattresses since the 1990s shift to pillow-top single-sided designs. Still made by Idle Sleep, Layla, Saatva Zenhaven, and Brooklyn Bedding Plank.

A flat, rigid platform that sits beneath a mattress for support, height, and airflow. Replaces the traditional box spring for most modern mattresses. Most foam and hybrid mattresses require a foundation, platform frame, or solid surface — not a traditional box spring which provides too much give.

A 1–10 scale indicating mattress feel from softest (1) to hardest (10). Standardized definitions: 1–3 is plush/soft, 4–5 is medium-soft, 5–6 is medium, 6–7 is medium-firm, 7–8 is firm, 8–10 is extra firm/hard. Not standardized across brands — a '6' from one brand may feel different from another's.

A commonly confused distinction. Firmness is the feel of the surface layer — how soft or hard it feels to touch. Support is how well the mattress maintains spinal alignment and prevents sinkage. A mattress can be soft (plush comfort layer) with strong support (firm coil core), or firm with poor support (cheap, compressing foam).

A layer in mattresses that meets federal flammability standards (16 CFR Part 1633). Conventional mattresses use chemical flame retardants (borate, antimony trioxide). Organic mattresses use natural wool as a fire barrier — wool chars rather than burning and can meet the standard without synthetic chemicals.

Memory foam infused with gel beads or swirled gel to increase thermal conductivity, pulling body heat away faster than standard memory foam. Measurably cooler than traditional memory foam but not as cool as latex or hybrid construction.

Foam with graphite (carbon) added to increase thermal conductivity. Used in brands like Nolah's AirFoam™. Graphite conducts heat away from the body, making the foam cooler than standard memory foam.

A UL certification (formerly GREENGUARD Children & Schools) with stricter VOC emission limits than standard GREENGUARD. Relevant for products used in environments where children or sensitive individuals are present. Many premium mattress brands carry this certification.

The international certification standard for organic latex, requiring that the latex contain at least 95% certified organic raw material. Issued by Control Union and Ecocert. Certifies both the latex content and the production process. The benchmark certification for natural latex mattresses.

The leading global standard for organic textiles, covering organic cotton and wool in mattress covers and comfort layers. Requires at least 95% certified organic fibers and prohibits toxic inputs throughout the supply chain. Certifies both the material and the manufacturing facility.

A brand tier system used by many mattress manufacturers to distinguish entry, mid-tier, and premium offerings within the same product family. The 'Good' tier is the most accessible; 'Best' is the flagship. This helps retailers structure conversations without overwhelming customers with too many choices.

Purple's hyper-elastic polymer grid technology. Behaves simultaneously as a firm support surface and a pressure-eliminating surface by buckling under concentrated pressure (hips, shoulders) while remaining rigid under distributed pressure (torso). Provides genuine temperature neutrality through large air channels.

Foam with a density rating above 1.8 lb/ft³ (typically 2.0–2.5+ lb/ft³). Higher density indicates more material per cubic foot, resulting in better durability, support, and longevity. Used in quality support layers and transitions.

A highly flexible synthetic polymer used in Purple's GelFlex® Grid. The material can flex to thousands of percent elongation without breaking, allowing the grid columns to buckle under pressure and recover instantly. Unlike foam, it has no memory — response is immediate.

A mattress combining a pocketed coil support core with foam or latex comfort layers of at least 2 inches. Delivers the pressure relief of foam/latex with the airflow, bounce, and edge support of coils. The most popular mattress category by revenue in the US.

A traditional upholstery technique where buttons or ties are pulled through a mattress by hand, compressing the comfort materials. Creates a distinctive dimpled appearance and keeps materials firmly in place. Associated with luxury brands like Aireloom, Stearns & Foster, and traditional European mattress makers.

The variation in time between heartbeats. Higher HRV during sleep indicates better recovery and parasympathetic nervous system activity. Measured by smart beds (Eight Sleep, Sleep Number) and wearables (Oura, Whoop). Poor sleep conditions (temperature, pressure) reduce HRV.

The standardized measure of foam firmness — the force (in pounds) required to indent 4 inches of foam by 25% using a 50 sq in plate. Lower ILD = softer; higher ILD = firmer. ILD 10–20 is plush; 25–31 is medium; 36+ is firm. Not correlated with density.

A resilient, bouncy material derived from rubber tree sap (natural latex) or petroleum-based chemicals (synthetic latex). Natural latex is used in premium mattresses for its durability, hypoallergenic properties, and eco-credentials. Processed as Dunlop or Talalay.

A viscoelastic polyurethane foam that responds to body heat and weight, slowly conforming to the sleeper's shape. Invented by NASA and commercialized in 1992 by Tempur-Pedic. Known for pressure relief and motion isolation; criticized for heat retention and slow response.

A mattress's ability to absorb movement on one side and prevent it from transferring to the other side. Critical for couples with different sleep schedules or restless sleepers. Memory foam and individually wrapped pocketed coils provide the best motion isolation; innerspring the worst.

A third-party certification screening products against a database of 6,500+ known or suspected harmful chemicals. Goes beyond most organic certifications in chemical depth. Naturepedic holds this certification. The most comprehensive chemical safety certification available for consumer products.

Manufacturer's Suggested Retail Price. The list price before discounts. In the mattress industry, most DTC brands maintain constant 'sale' pricing that may represent a discount from inflated MSRP. Comparing sale prices (rather than MSRP discounts) is more meaningful for apples-to-apples comparison.

Latex derived from the sap of Hevea brasiliensis (rubber trees). Certified natural latex holds GOLS (Global Organic Latex Standard) certification. More durable and eco-friendly than synthetic latex, with natural antimicrobial and hypoallergenic properties.

Foam with a cell structure where the cell walls are broken, allowing air to move through the foam. More breathable and temperature-neutral than traditional closed-cell foam. Most modern premium foam mattresses use open-cell construction.

Cotton grown without synthetic pesticides, herbicides, or fertilizers. When used in mattress covers and comfort layers, it's typically GOTS-certified. Softer and more breathable than conventional cotton; relevant for eco-conscious buyers and those sensitive to chemicals.

Wool from sheep raised on certified organic land without synthetic chemicals. Used as a natural fire barrier and temperature regulator in premium mattresses, replacing chemical flame retardants. GOTS certification applies to organic wool in mattress applications.

A coil type where the top and bottom of each coil are squared off (not circular) to allow a hinging motion. More conforming than Bonnell coils and more durable than many pocketed designs. Used in some premium retail mattresses including certain Sealy models.

The release of volatile organic compounds (VOCs) from new foam mattresses, causing the characteristic 'new mattress smell.' Typically dissipates within 24–72 hours. CertiPUR-US® and GREENGUARD Gold certifications indicate low VOC emissions. Ventilating the room for 24 hours after unboxing accelerates dissipation.

A global textile certification (Oeko-Tex Standard 100) testing for harmful substances including heavy metals, pesticides, formaldehyde, and pH. Relevant for mattress covers and fabric components. Not organic certification — it screens for harmful substances in both organic and conventional textiles.

A substance that absorbs and releases heat energy during phase transitions (usually solid-liquid). When woven into mattress covers or infused in foam, PCM absorbs body heat at a set temperature, creating a cooling effect. Found in brands like Cocoon by Sealy (Chill) and Bear.

A coil type where each spring is individually encased in fabric. Each coil moves independently, providing better motion isolation than interconnected coils and better conforming to body contours. Also called 'Marshall coils' or 'wrapped coils.' The standard in hybrid mattresses.

An additional plush comfort layer stitched to the top of a mattress, creating a visible, raised appearance at the top edge. Adds immediate plushness but can compress or shift over time more than a Euro top. Common in traditional innerspring and hybrid luxury models.

A mattress's ability to reduce peak pressure at contact zones (shoulders, hips, heels, knees). Measured in mmHg via pressure-mapping equipment. Mattresses with high pressure relief allow pressure points to distribute load across a larger surface area, reducing pain and improving circulation.

A bed frame with a solid or slatted surface that supports the mattress directly, eliminating the need for a box spring or foundation. Slats should be no more than 3 inches apart for adequate foam support. Most modern DTC mattresses are designed for platform frames.

A measurement technique using a grid of pressure sensors between a body and the mattress surface, producing a color map of pressure distribution. Areas of concentrated pressure (red/hot) indicate high-pressure zones. Used to verify pressure relief claims and compare mattresses scientifically.

Sealy's proprietary support technology engineered with orthopedic physician input to provide reinforced support in the center third of the mattress (where the lumbar region rests). Aims to maintain neutral spinal alignment by preventing hip sinkage in the lumbar zone.

How quickly a mattress returns to its original shape after pressure is removed. Latex and coils have near-instant response (< 1 second). Traditional memory foam has slow response (3–10 seconds), reducing the 'stuck' sensation during position changes. Modern gel foam falls between.

A certification ensuring that agricultural products (including rubber/latex) are sourced from farms meeting sustainability standards for biodiversity, ecosystem services, and worker welfare. Used by Awara and Birch for their latex sourcing.

Rapid Eye Movement sleep — the stage characterized by vivid dreams, emotional processing, and memory consolidation. Occurs primarily in the later portion of the night. Poor sleep surface quality disrupts REM by causing awakenings and discomfort, reducing the proportion of sleep spent in REM.

Latex manufactured from petroleum-derived chemicals, primarily styrene-butadiene rubber (SBR). Cheaper than natural latex but lacks its durability, eco-credentials, and natural properties. Often blended with natural latex in 'blended latex' products.

The bottom layer of a mattress that provides structural support and maintains the sleep surface. Can be pocketed coils (hybrid/innerspring), high-density foam (all-foam), latex (all-latex), or air chambers (adjustable air). Determines primary support characteristics.

The degree to which a mattress maintains neutral spinal alignment (ears, shoulders, hips, and knees on the same horizontal plane) in the sleeper's primary position. Poor alignment causes lumbar strain and morning stiffness. Critical performance factor especially for back and stomach sleepers.

A period during which a customer can return a mattress for a full refund after sleeping on it at home. Industry standard is 100 nights; some brands offer 120, 365, or 540 nights. Returns typically involve free pickup rather than repacking the compressed mattress.

Two Twin XL mattresses side by side in a King frame, allowing independent firmness and adjustable base settings on each side. The standard configuration for couples who use adjustable bases or have significantly different firmness preferences. See the Sizes guide for full details.

Sleep cycles through four stages: N1 (light sleep), N2 (consolidated sleep), N3 (deep/slow-wave sleep), and REM (rapid eye movement). A full cycle takes ~90 minutes; adults cycle through 4–6 times nightly. Mattress comfort affects both sleep onset time and depth of N3 and REM.

A collection of behavioral and environmental practices that promote consistent, quality sleep. Includes consistent sleep/wake times, dark cool bedroom, avoiding screens before bed, and limiting caffeine. A high-quality mattress is part of sleep hygiene, but not a substitute for behavioral practices.

The primary position in which a person sleeps. Three main positions — side, back, and stomach — each have distinct mattress requirements. Side sleeping is most common (~54% of adults); back sleeping is considered most spine-friendly; stomach sleeping is most stressful for the lumbar and cervical spine.

A premium latex processing method adding vacuum and freeze-flash steps to Dunlop's pour-and-bake process, creating a lighter, more consistent, airier foam. Softer and more pressure-relieving than Dunlop; more expensive to produce.

A foam layer between the comfort and support layers that gradually changes firmness properties. Prevents sleepers from feeling the hard support core through the softer comfort layer. Higher quality mattresses use dedicated transition layers; budget options skip this.

See Sleep Trial. The number of nights a customer can test a mattress before deciding to keep or return it. Longer trials (365+) indicate high brand confidence in their product and are associated with premium brands like Nectar, DreamCloud, Avocado, and Saatva.

Tempur-Pedic's proprietary viscoelastic foam, developed from NASA pressure-absorbing research. Denser and more temperature-sensitive than generic polyurethane memory foam. Responds to body heat and weight to conform precisely. Not replicated by competitors — generic 'memory foam' is polyurethane with a different formula.

A material property combining viscous (slow-flowing) and elastic (spring-returning) characteristics. Memory foam is viscoelastic — it slowly conforms to pressure (viscous) and slowly recovers its shape after pressure is removed (elastic). Temperature affects the rate of response.

Carbon-containing chemicals that evaporate at room temperature. In mattresses, VOCs are emitted from foam materials during off-gassing. Levels regulated by CertiPUR-US®, GREENGUARD Gold, and GREENGUARD standards. Health effects depend on specific compound, concentration, and duration of exposure.

A delivery service that includes setup of the mattress in your bedroom and removal of your old mattress, performed by a two-person team. Standard with Saatva and some Stearns & Foster orders. Most DTC brands do curbside delivery only.

A manufacturer's guarantee covering defects in materials or workmanship for a specified period. For mattresses, this typically covers visible sagging or body impressions deeper than 1–1.5 inches. Most warranties are prorated after year one. Lifetime warranties are offered by Nectar, DreamCloud, WinkBed, and Nolah.

A mattress construction where different areas of the mattress have different firmness or support levels. Commonly firmer under the hips/torso and softer under the shoulders. Found in Helix, Casper Wave, and Tempur-Pedic ProAdapt. Addresses the need for simultaneous shoulder and hip comfort.