The evidence
Each criterion with what we found, where we found it and when. Anything we could not confirm says so.
NTH criteria
NTH Framework v1.2. Score 75.4 (raw 57.0 of 100), calibrated so the best hotel in this edition (Santa Monica Proper Hotel) reads 90. Evidence retrieved 2026-10-22.
Sleep12.0 / 24
The room as an instrument for deep, uninterrupted, circadian-aligned rest.
Mattress & sleep system
Hotel-reported · in the best room
Naturalmat organic mattress listed across room categories.
Bedding & textiles
Hotel-reported · in the best room
Organic cotton sheets; temperature-regulating pillows and duvets.
Sleep programme & pillow menu
Hotel-reported · in the best room
Sleep programme with tracker data, consultation, yoga nidra.
Blackout
Not yet reviewed · in the best room
Unknown. We have asked the hotel.
0.0 / 2 pts
Unknown
Circadian & warm evening lighting
Not yet reviewed · in the best room
Unknown. We have asked the hotel.
0.0 / 2 pts
Unknown
In-room red light
Not yet reviewed · in the best room
Unknown. We have asked the hotel.
0.0 / 2 pts
Unknown
Acoustic quiet
Not yet reviewed · in the best room
Unknown. We have asked the hotel.
0.0 / 4 pts
Unknown
EMF & Wi-Fi-off options
Not yet reviewed · in the best room
Unknown. We have asked the hotel.
0.0 / 2 pts
Unknown
Air2.0 / 12
What you breathe for eight hours a night: filtered, fresh, smoke-free and unperfumed.
In-room purification
Not yet reviewed · in the best room
Unknown. We have asked the hotel.
0.0 / 5 pts
Unknown
Ventilation & building standard
Hotel-reported · across the property
Part of the BREEAM-certified Whiteley redevelopment.
Smoke-free policy
Not yet reviewed · across the property
Unknown. We have asked the hotel.
0.0 / 2 pts
Unknown
Fragrance-free & low-allergen rooms
Not yet reviewed · in the best room
Unknown. We have asked the hotel.
0.0 / 2 pts
Unknown
Water3.0 / 12
Clean water to drink, and to shower and bathe in.
Filtered drinking water
Hotel-reported · in the best room
In-house filtered water refill programme.
Shower & bath filtration
Not yet reviewed · in the best room
Unknown. We have asked the hotel.
0.0 / 5 pts
Unknown
Gentler pool & hydrotherapy water
Not met · across the property
Magnesium pool announced, but the indoor pool and thermal suite were 'not yet open' on 2026-10-22. Re-score on opening.
Nourishment7.0 / 10
Food and drink that heal rather than merely please.
Organic & local sourcing
Hotel-reported · across the property
Local UK producers and small-scale suppliers.
Clean-ingredient standard
Hotel-reported · across the property
Plant-forward menus; Eat With Six Senses nutrition programme.
Clean minibar & in-room hydration
Hotel-reported · in the best room
Filtered water in reusable bottles; no single-use plastic.
Nutrition guidance
Hotel-reported · across the property
Nutrition advice within programmes.
Movement7.0 / 10
The means to train, stretch and move, indoors and out.
Gym completeness
Hotel-reported · across the property
325 sq m fitness centre, 24/7.
Classes & studios
Hotel-reported · across the property
Yoga and mindful movement studios; aerial yoga.
Swimming
Not met · across the property
20 m pool not yet open on 2026-10-22.
Outdoor activity
Not yet reviewed · across the property
Unknown. We have asked the hotel.
0.0 / 2 pts
Unknown
Holistic Wellness18.0 / 19
Healing traditions and the recovery technology that complements them.
Spa facility
Hotel-reported · across the property
2,300 sq m spa, 13 treatment rooms, Turkish hammam.
Traditional & integrative modalities
Hotel-reported · across the property
HUM2N functional/longevity medicine, hormone optimisation, European herbalism (Alchemy Bar), energy treatments.
Mind & breath
Hotel-reported · across the property
Yoga nidra, breathwork, meditation, sound loungers.
Heat therapy
Hotel-reported · across the property
Hammam; thermal suite not yet open.
Cold therapy
Hotel-reported · across the property
Cryotherapy.
Photobiomodulation & PEMF
Hotel-reported · across the property
Red-light therapies; PEMF in the Biohack Recovery Lounge.
Clinical longevity (IV, HBOT, diagnostics)
Hotel-reported · across the property
HUM2N blood diagnostics and IV nutrient therapy; hyperbaric chamber.
Materials & Setting8.0 / 13
What touches the skin and surrounds the stay: finishes, products, cleaning, and the landscape beyond the door.
Natural, low-VOC finishes
Hotel-reported · in the best room
Warm woods; natural-materials Earth Lab.
Clean bath & body amenities
Hotel-reported · in the best room
La-Eva bathroom amenities.
Non-toxic spa & nail products
Hotel-reported · across the property
House-made herbal preparations from the Alchemy Bar used in treatments.
Non-toxic housekeeping & plastic-free operations
Hotel-reported · across the property
Operates without single-use plastic.
Green & blue space
Hotel-reported · across the property
Near Hyde Park; 1,150 sq m of green roof.
Walkability & low-impact mobility
Hotel-reported · across the property
Walkable to Hyde Park and Notting Hill.
Our review
At a glance
- Fragrance
- 5 not yet reviewed
- Air
- 5 not yet reviewed
- Cleaning & care
- 4 not yet reviewed
- Sleep & materials
- 5 not yet reviewed
- Water & pools
- 4 not yet reviewed
- Food
- 2 not yet reviewed
- Light & quiet
- 2 not yet reviewed
- Building
- 3 not yet reviewed
Nothing reviewed yet: every criterion is shown as not yet reviewed.
Nothing reviewed yet25 of 25 not yet reviewed
Counts cover the 25 scored criteria; the other 5 windows are context.
Checked
Read the full profileThe ledger
Fragrance
Added scent is the most common complaint from sensitive guests, and the hardest thing to see on a booking page.
No added fragrance in rooms
Not yet reviewed.
So far, the hotel says: The hotel describes ‘art, scent, and light woven into the details of your space’.
Our note. Whether rooms are scented, and with what, is not stated.
How we know
What we look for. No air fresheners, plug-ins, room sprays or diffusers used in guest rooms.
Why it matters. In a US population survey, about a third of adults reported health problems, such as migraine and breathing difficulty, from fragranced products. Terpenes in many fragrances also react with indoor ozone to form fine particles and formaldehyde.
Sources: Steinemann, Air Quality, Atmosphere & Health, Fragranced consumer products: exposures and effects from emissions (); Nazaroff & Weschler, Atmospheric Environment, Cleaning products and air fresheners: exposure to primary and secondary air pollutants ()
Source 1: Hotel website: home pageUndated · read 22 Oct 2026
No scent marketing
Not yet reviewed.
Fragrance-free laundry
Not yet reviewed.
Unscented bath products
Not yet reviewed.
So far, the hotel says: Room features list ‘sustainable bathroom amenities’.
Our note. Whether an unscented option exists is not stated.
How we know
What we look for. Fragrance-free toiletries in the room by default, or on request.
Why it matters. Fragrance ingredients are among the most frequent causes of allergic contact reactions to cosmetics. An unscented option lets sensitive guests use what is provided instead of packing their own.
Source: EU Scientific Committee on Consumer Safety, Opinion on fragrance allergens in cosmetic products ()
Source 2: Hotel website: accommodationUndated · read 22 Oct 2026
Unscented spa options
Not yet reviewed.
So far, the operator said in 2026: Herbs from the Alchemy Bar become ‘tinctures and tonics used across treatments, restaurants and bars, and steam and hammam rituals’.
Our note. Whether treatments and the hammam can be had without scent is not stated.
How we know
What we look for. Treatments, saunas and steam rooms available without essential oils or scent infusions.
Why it matters. Essential oils are fragrance: the EU’s scientific committee lists several natural extracts, as well as single fragrance chemicals, among established contact allergens. A shared sauna with a scent infusion is hard to avoid.
Source: EU Scientific Committee on Consumer Safety, Opinion on fragrance allergens in cosmetic products ()
Source 3: Six Senses opening press release (Luxury Hospitality Daily)13 Mar 2026 · read 22 Oct 2026
Know something about fragrance here that we don’t? Tell us
Air
What you breathe for eight hours a night: smoke history, fresh air, filtration and anything burning in the room.
Smoke-free property
Not yet reviewed.
Opening windows
Not yet reviewed.
So far, a press report says: A reviewer’s suite had ‘hefty Crittall doors leading onto a grand balcony’.
Our note. Seen in one terrace suite; the hotel does not describe windows across its rooms.
How we know
What we look for. Guest rooms have windows or doors that open to outside air.
Why it matters. The US EPA lists opening windows, when outdoor air allows, as a way to dilute pollutants released indoors. An opening window lets guests air a room themselves when it smells of cleaning products or new furnishings.
Source: US EPA, Improving indoor air quality ()
Source 4: Mr & Mrs Smith: hotel reviewUndated · read 22 Oct 2026
Filtered fresh air
Not yet reviewed.
In-room air purifier
Not yet reviewed.
No in-room combustion
Not yet reviewed.
Know something about air here that we don’t? Tell us
Cleaning & care
How a room is cleaned, treated and prepared, and whether a request for a gentler clean is actually honored.
Low-chemical housekeeping
Not yet reviewed.
No ozone or biocide treatments
Not yet reviewed.
Low-chemical pest control
Not yet reviewed.
Sensitive-guest preparation
Not yet reviewed.
Know something about cleaning & care here that we don’t? Tell us
Sleep & materials
The textiles, mattress and floor you spend the night closest to, and how allergen-aware the room is.
Tested or organic bed linen
Not yet reviewed.
So far, the hotel says: The hotel lists ‘organic cotton sheets’ among its sleep tools.
Our note. No organic or residue-testing certification is named.
How we know
What we look for. Sheets and towels certified to a residue-testing standard such as OEKO-TEX Standard 100, or certified organic.
Why it matters. Certifications such as OEKO-TEX Standard 100 test the finished fabric, down to the thread, against a list of restricted substances, which lowers skin exposure over a night’s sleep.
Source: OEKO-TEX, OEKO-TEX Standard 100 (undated)
Source 2: Hotel website: accommodationUndated · read 22 Oct 2026
Mattress materials disclosed
Not yet reviewed.
So far, the hotel says: Room features list a ‘Naturalmat organic mattress’, and the hotel speaks of ‘handmade mattresses’.
Our note. The materials and how flame-retardancy is achieved are not stated.
How we know
What we look for. The hotel says what its mattresses are made of and how flame-retardancy is achieved.
Why it matters. Flame retardants have been added to mattresses and seating foam, and the US National Institute of Environmental Health Sciences lists possible effects including endocrine and thyroid disruption. How much a mattress adds to anyone’s exposure is still debated; disclosure lets guests choose.
Source: US National Institute of Environmental Health Sciences, Flame retardants (undated)
Source 2: Hotel website: accommodationUndated · read 22 Oct 2026
Hard floors
Not yet reviewed.
So far, a press report says: A reviewer’s suite had a parquet floor.
Our note. Seen in one suite; flooring in other rooms is not described.
How we know
What we look for. Hard, cleanable floors in guest rooms rather than wall-to-wall carpet.
Why it matters. Dust mites live in carpet, and US health guidance for allergic sleepers is to replace wall-to-wall carpet in bedrooms with bare floors, which can be cleaned completely between guests.
Source: US National Institute of Environmental Health Sciences, Dust mites and cockroaches (undated)
Source 4: Mr & Mrs Smith: hotel reviewUndated · read 22 Oct 2026
Allergy-friendly rooms
Not yet reviewed.
Pet-free rooms
Not yet reviewed.
So far, the hotel says: ‘Four-legged friends up to 7 kg are welcome, free of charge.’
Our note. Whether any rooms are kept pet-free is not stated.
How we know
What we look for. Rooms or floors where animals are never allowed, cleaned to a separate routine.
Why it matters. Pet allergen can stay on carpets and furniture for months and travels on clothing. For allergic guests a room animals never enter matters more than any amenity.
Source: US National Institute of Environmental Health Sciences, Pet allergens (undated)
Source 2: Hotel website: accommodationUndated · read 22 Oct 2026
Know something about sleep & materials here that we don’t? Tell us
Water & pools
Drinking water, shower water and pool air.
Filtered or tested drinking water
Not yet reviewed.
So far, the hotel says: The hotel lists ‘high-quality water filtered and bottled in-house’.
Our note. The filter type and how often filters are changed or the water tested are not stated.
How we know
What we look for. Drinking water filtered at the tap or refill station, or treated and tested on site, with filters or tests on a schedule.
Why it matters. Public water systems in California are regulated and monitored by the State Water Board, though older building plumbing can still affect what reaches the tap. Filtration mainly improves taste and removes chlorine, and it replaces single-use bottles; private wells need regular testing.
Source: California State Water Resources Control Board, Division of Drinking Water (undated)
Source 5: Hotel website: sustainabilityUndated · read 22 Oct 2026
Water safety plan
Not yet reviewed.
Shower filters
Not yet reviewed.
Shown for information; not scored.
Outdoor or low-chloramine pools
Not yet reviewed.
So far, the hotel says: ‘Final touches are still underway on the indoor pool and thermal suite, which are not yet open.’
Our note. Read on an archived copy of the page from July 2026. How the pool will be ventilated and monitored is not stated.
Shown for information; not scored.
How we know
What we look for. Pools are outdoors, or indoor pools have dedicated ventilation and monitored combined chlorine.
Why it matters. Chloramines irritate the skin, eyes and airways, and they build up in the air of indoor pools without enough ventilation. Outdoor pools, and good ventilation for indoor ones, keep levels low.
Source: US CDC, Chloramines and pool operation ()
Source 2: Hotel website: accommodationUndated · read 22 Oct 2026
Context, not scored: almost every pool in this catalog is outdoors, so it says little about one hotel against another.
Know something about water & pools here that we don’t? Tell us
Food
Allergen care first; where the produce comes from second.
Allergen-aware kitchen
Not yet reviewed.
Garden or organic produce
Not yet reviewed.
So far, the hotel says: The kitchen aims to source ‘more than 80 percent of ingredients from the UK’, including eggs from Orchard Eggs, ‘a biodynamic farm in East Sussex’.
Our note. Local sourcing, not an organic commitment; there is no kitchen garden.
Shown for information; not scored.
How we know
What we look for. A meaningful share of the kitchen’s produce is grown on site or certified organic.
Why it matters. A large review found detectable pesticide residues about four times as often in conventional crops as in organic ones. Over a short stay the difference in exposure is small, so we show this as a note on the kitchen, not a scored health factor.
Source: Barański et al., British Journal of Nutrition, Higher antioxidant and lower cadmium concentrations and lower incidence of pesticide residues in organically grown crops: a systematic literature review and meta-analyses ()
Source 5: Hotel website: sustainabilityUndated · read 22 Oct 2026
Kitchen note, not scored.
Know something about food here that we don’t? Tell us
Light & quiet
Darkness and silence at night, and radio-quiet options for guests who want them.
Darkness and quiet
Not yet reviewed.
Radio-quiet options
Not yet reviewed.
Shown for information; not scored.
Know something about light & quiet here that we don’t? Tell us
Building
The materials a hotel was built and renovated with, how it handles damp, and what third parties have certified.
Low-emitting materials
Not yet reviewed.
Leak and mold response
Not yet reviewed.
Building certification
Not yet reviewed.
So far, the operator said in 2026: ‘Six Senses London forms part of the BREEAM-certified redevelopment of The Whiteley London.’
Our note. No rating level or year is given, and we have not found the certificate.
Shown for information; not scored.
How we know
What we look for. A third-party certification such as WELL, LEED or a green business program, recorded with its level, and its year where the certifier gives one.
Why it matters. WELL assesses air, water and light in occupied buildings. LEED and green business programs are mainly environmental, with some indoor-quality elements. A certificate records what was designed or checked at a point in time, not what a room is like today.
Source 3: Six Senses opening press release (Luxury Hospitality Daily)13 Mar 2026 · read 22 Oct 2026
Context only. A certificate supports specific criteria only where its scope covers them.
Know something about building here that we don’t? Tell us
Notes & sources
- Hotel website: home page, Undated · read 22 Oct 2026
- Hotel website: accommodation, Undated · read 22 Oct 2026
- Six Senses opening press release (Luxury Hospitality Daily), 13 Mar 2026 · read 22 Oct 2026
- Mr & Mrs Smith: hotel review, Undated · read 22 Oct 2026
- Hotel website: sustainability, Undated · read 22 Oct 2026
- Hotel website: spa, Undated · read 22 Oct 2026
- Hotel website: sleep programme, Undated · read 22 Oct 2026
Room count: Per the hotel’s website: rooms and suites, alongside 14 branded residences. Hotel website (opens the hotel’s website)
Photographs: Six Senses London; Six Senses London; Six Senses London; Six Senses London; Six Senses London; Six Senses London
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