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 43.9 (raw 33.2 of 100), calibrated so the best hotel in this edition (Santa Monica Proper Hotel) reads 90. Evidence retrieved 2026-10-22.
Sleep2.0 / 24
The room as an instrument for deep, uninterrupted, circadian-aligned rest.
Mattress & sleep system
Not yet reviewed · in the best room
Unknown. We have asked the hotel.
0.0 / 5 pts
Unknown
Bedding & textiles
Not yet reviewed · in the best room
Unknown. We have asked the hotel.
0.0 / 4 pts
Unknown
Sleep programme & pillow menu
Hotel-reported · in the best room
Pillow menu; optional mattress toppers.
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
Air1.0 / 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
Not yet reviewed · across the property
Unknown. We have asked the hotel.
0.0 / 3 pts
Unknown
Smoke-free policy
Hotel-reported · across the property
No smoking in rooms or public areas; designated smoking areas.
Fragrance-free & low-allergen rooms
Not yet reviewed · in the best room
Unknown. We have asked the hotel.
0.0 / 2 pts
Unknown
Water0.0 / 12
Clean water to drink, and to shower and bathe in.
Filtered drinking water
Not yet reviewed · in the best room
Unknown. We have asked the hotel.
0.0 / 5 pts
Unknown
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 yet reviewed · across the property
Unknown. We have asked the hotel.
0.0 / 2 pts
Unknown
Nourishment2.2 / 10
Food and drink that heal rather than merely please.
Organic & local sourcing
Not yet reviewed · across the property
Unknown. We have asked the hotel.
0.0 / 4 pts
Unknown
Clean-ingredient standard
Hotel-reported · across the property
Plant-based detox nutrition.
Clean minibar & in-room hydration
Not yet reviewed · in the best room
Unknown. We have asked the hotel.
0.0 / 2 pts
Unknown
Nutrition guidance
Hotel-reported · across the property
Naturopaths and nutrition tools within programmes.
Movement7.0 / 10
The means to train, stretch and move, indoors and out.
Gym completeness
Hotel-reported · across the property
Shakti Fitness Centre, 7am to 8pm.
Classes & studios
Hotel-reported · across the property
Daily classes: yoga, Pilates (reformer), Tai Chi, Qi Gong, pranayama; yoga pavilion.
Swimming
Hotel-reported · across the property
Lap and relaxation pools.
Outdoor activity
Hotel-reported · across the property
Beach access.
Holistic Wellness15.0 / 19
Healing traditions and the recovery technology that complements them.
Spa facility
Hotel-reported · across the property
Steam caverns; treatment-room count not published.
Traditional & integrative modalities
Hotel-reported · across the property
TCM, Ayurveda, Thai traditional medicine, naturopathy.
Mind & breath
Hotel-reported · across the property
Meditation (monks' cave), pranayama, binaural sound healing.
Heat therapy
Hotel-reported · across the property
Steam caverns.
Cold therapy
Hotel-reported · across the property
Hot and cold plunge pools.
Photobiomodulation & PEMF
Not yet reviewed · across the property
Unknown. We have asked the hotel.
0.0 / 2 pts
Unknown
Clinical longevity (IV, HBOT, diagnostics)
Hotel-reported · across the property
IV therapy, hyperbaric oxygen therapy and diagnostics.
Materials & Setting6.0 / 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
Natural furnishings in rooms set among granite boulders and forest.
Clean bath & body amenities
Hotel-reported · in the best room
Natural bath amenities; formulation not disclosed.
Non-toxic spa & nail products
Not yet reviewed · across the property
Unknown. We have asked the hotel.
0.0 / 2 pts
Unknown
Non-toxic housekeeping & plastic-free operations
Not yet reviewed · across the property
Unknown. We have asked the hotel.
0.0 / 2 pts
Unknown
Green & blue space
Hotel-reported · across the property
Beachfront on Laem Set; tropical gardens.
Walkability & low-impact mobility
Not yet reviewed · across the property
Unknown. We have asked the hotel.
0.0 / 2 pts
Unknown
Our review
At a glance
- Fragrance
- 5 not yet reviewed
- Air
- 1 hotel-reported, 4 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
One reported by the hotel; the rest not yet reviewed.
1 hotel-reported24 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.
No scent marketing
Not yet reviewed.
Fragrance-free laundry
Not yet reviewed.
Unscented bath products
Not yet reviewed.
So far, the hotel says: Rooms come with ‘signature Kamalaya bath amenities’; the FAQ describes ‘a range of natural amenities’: shampoo, conditioner, body lotion and liquid soap.
Our note. Whether they are scented, or an unscented set is offered, is not stated. Ask before you arrive.
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 1: Hotel website: Hillside Room Garden ViewUndated · read 22 Oct 2026
Unscented spa options
Not yet reviewed.
So far, the hotel says: The Three Treasures treatment includes ‘aromatherapy using Kamalaya’s bespoke “Three Treasures” oil blends’.
Our note. This shows some treatments are scented; whether unscented options and unscented steam are offered 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 2: Hotel website: Sleep Enhancement programmeUndated · 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.
So far, the hotel says: Guests are asked to ‘refrain from smoking in your room’; smoking is not permitted in restaurants or public areas, and is allowed in a sala by the entrance and a designated area behind the beach attendant’s building.
Our note. Rooms are a request rather than a ban, and balconies are not mentioned, so this falls short of the criterion.
How we know
What we look for. No smoking in any guest room, balcony or indoor space.
Why it matters. Tobacco smoke leaves a residue (thirdhand smoke) on surfaces and in dust. A study of California hotels found that non-smoking rooms in hotels that allow smoking elsewhere did not protect non-smoking guests from it.
Source: Matt et al., Tobacco Control, Thirdhand smoke and exposure in California hotels: non-smoking rooms fail to protect non-smoking hotel guests from tobacco smoke exposure ()
Source 3: Hotel website: FAQsUndated · read 22 Oct 2026
Opening windows
Hotel-reportedonly some rooms or areas
The hotel says: ‘Guest accommodation, open-air treatment rooms and yoga pavilions are designed to maximise natural airflow, reducing reliance on air conditioning.’
Our note. Windows that open are not described room by room; the Hillside Room Garden View lists a balcony. Ask for a room with outside space.
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: Hotel website: sustainability practicesUndated · read 22 Oct 2026
Filtered fresh air
Not yet reviewed.
In-room air purifier
Not yet reviewed.
No in-room combustion
Not yet reviewed.
So far, the hotel says: ‘Eco-friendly cleaning products, together with environmentally friendly mosquito spray and coils, are used across the sanctuary.’
Our note. Mosquito coils burn; where they are used is not stated. Ask whether coils are lit in or near the rooms.
How we know
What we look for. No gas fireplaces, candles or incense in guest rooms.
Why it matters. In homes with gas appliances, the US EPA notes that indoor nitrogen dioxide often exceeds outdoor levels, and that it irritates the eyes, nose, throat and airways. Candles and incense burn in the same small, closed room.
Source: US EPA, Nitrogen dioxide’s impact on indoor air quality ()
Source 4: Hotel website: sustainability practicesUndated · read 22 Oct 2026
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.
So far, the hotel says: ‘Eco-friendly cleaning products … are used across the sanctuary.’
Our note. The products are not named, and scent, hazard and aerosols are not described.
How we know
What we look for. Unscented, low-hazard cleaning products and no aerosols, with a product list the hotel will share.
Why it matters. In a ten-country study, weekly use of household cleaning sprays was linked to new asthma symptoms in adults. Residue and scent from cleaning also linger for the next guest.
Source: Zock et al., American Journal of Respiratory and Critical Care Medicine, The use of household cleaning sprays and adult asthma: an international longitudinal study ()
Source 4: Hotel website: sustainability practicesUndated · read 22 Oct 2026
No ozone or biocide treatments
Not yet reviewed.
Low-chemical pest control
Not yet reviewed.
So far, the hotel says: ‘Environmentally friendly mosquito spray and coils’ are used across the sanctuary.
Our note. This describes products, not a monitoring-and-sealing approach.
How we know
What we look for. Pests handled by monitoring, sealing and targeted treatment rather than routine spraying.
Why it matters. Integrated pest management uses monitoring, prevention and targeted controls, with broad spraying of pesticides as a last resort, which keeps chemical use indoors to what is needed.
Source: US EPA, Integrated pest management (IPM) principles ()
Source 4: Hotel website: sustainability practicesUndated · read 22 Oct 2026
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.
Mattress materials disclosed
Not yet reviewed.
So far, the hotel says: All accommodation offers ‘a pillow menu and optional mattress toppers’, chosen on the pre-arrival guest profile form.
Our note. Mattress materials and flame-retardancy are not described.
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 3: Hotel website: FAQsUndated · read 22 Oct 2026
Hard floors
Not yet reviewed.
Allergy-friendly rooms
Not yet reviewed.
So far, the hotel says: All accommodation offers ‘a pillow menu and optional mattress toppers’.
Our note. Barrier covers and feather-free, hot-washable bedding are not described.
How we know
What we look for. Allergen-barrier mattress and pillow covers and feather-free, hot-washable bedding, in all or designated rooms.
Why it matters. For dust-mite allergy, US health guidance is to encase mattresses and pillows in allergen-proof covers and wash bedding weekly in hot water (130–140 °F, about 55–60 °C).
Source: US National Institute of Environmental Health Sciences, Dust mites and cockroaches (undated)
Source 3: Hotel website: FAQsUndated · read 22 Oct 2026
Pet-free rooms
Not yet reviewed.
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: ‘Drinking water comes in recyclable glass bottles and guests are gifted with refillable water bottles upon arrival.’
Our note. Whether the water is filtered or treated on site, and how it is tested, is 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 4: Hotel website: sustainability practicesUndated · 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: A 25-metre lap pool beside the fitness centre, with ‘panoramic views of the nearby islands’, and a leisure pool ‘intertwined with the natural lotus ponds’.
Our note. The page does not say how the pools are treated.
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 5: Hotel website: beach and poolsUndated · 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.
So far, the hotel says: ‘Kamalaya cuisine offers menu options for all dietary preferences’; dietary requests go on the pre-arrival guest profile form.
Our note. Allergen labelling and cross-contact steps are not described.
How we know
What we look for. Menus labeled for major allergens, with documented steps to prevent cross-contact.
Why it matters. Most food-allergy reactions are mild, but any can progress to anaphylaxis, which can be life-threatening. US law recognizes nine major allergens; clear labeling and kitchen discipline are what keep a guest safe.
Source: US FDA, Food allergies: what you need to know ()
Source 3: Hotel website: FAQsUndated · read 22 Oct 2026
Garden or organic produce
Not yet reviewed.
So far, the hotel says: Menus are built around local, seasonal produce, ‘with organic and ethically sourced ingredients selected whenever feasible’; hydroponic vegetables come from Thai partners.
Our note. No share of organic or home-grown produce is given.
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 4: Hotel website: sustainability practicesUndated · 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.
So far, the hotel says: Rooms include a sleeping mask, and there are no televisions in guest rooms ‘to optimise the opportunities for rest and relaxation’.
Our note. Blackout shades and sound insulation are not described.
How we know
What we look for. Blackout shades and sound insulation that let the room become properly dark and quiet.
Why it matters. Night-time noise fragments sleep; the WHO’s night noise guidelines set a target of 40 dB outside the bedroom. A dark, quiet room is the simplest sleep aid there is.
Source: WHO Regional Office for Europe, Night noise guidelines for Europe ()
Source 1: Hotel website: Hillside Room Garden ViewUndated · read 22 Oct 2026
Radio-quiet options
Not yet reviewed.
So far, the hotel says: ‘There is no WiFi available in public areas’; the FAQ says Wi-Fi is ‘intentionally weak’ there and that all guest rooms have complimentary Wi-Fi.
Our note. Whether Wi-Fi can be switched off in a room is not stated. Listed as an amenity only.
Shown for information; not scored.
How we know
What we look for. Wi-Fi that can be switched off in the room, or a wired connection. Listed as an amenity only.
Why it matters. Some guests prefer lower radio exposure. The WHO says current evidence does not confirm any health effects from low-level electromagnetic fields, so we list these options as amenities, not as health benefits.
Source: World Health Organization, Radiation: electromagnetic fields ()
Source 4: Hotel website: sustainability practicesUndated · read 22 Oct 2026
Not part of any health score. Shown as an amenity at the guest’s preference.
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.
So far, the hotel says: ‘Indigenous wood, rather than teak … has been used throughout the property.’
Our note. Paints, adhesives, finishes and flooring are not described.
How we know
What we look for. Low-VOC paints, adhesives, finishes and flooring specified in construction or renovation.
Why it matters. Paints, varnishes and adhesives release volatile organic compounds, formaldehyde among them, most heavily when new. Low-emitting products reduce that load.
Source: US EPA, Volatile organic compounds’ impact on indoor air quality ()
Source 4: Hotel website: sustainability practicesUndated · read 22 Oct 2026
Leak and mold response
Not yet reviewed.
Building certification
Not yet reviewed.
Shown for information; not scored.
Know something about building here that we don’t? Tell us
Notes & sources
- Hotel website: Hillside Room Garden View, Undated · read 22 Oct 2026
- Hotel website: Sleep Enhancement programme, Undated · read 22 Oct 2026
- Hotel website: FAQs, Undated · read 22 Oct 2026
- Hotel website: sustainability practices, Undated · read 22 Oct 2026
- Hotel website: beach and pools, Undated · read 22 Oct 2026
- Hotel website: about Kamalaya, Undated · read 22 Oct 2026
- Hotel website: Cognitive House, Undated · read 22 Oct 2026
- Hotel website: Longevity House, Undated · read 22 Oct 2026
Room count: Not stated on the hotel’s own site. Hotel website (opens the hotel’s website)
Photographs: Kamalaya Koh Samui; Kamalaya Koh Samui; Kamalaya Koh Samui; Kamalaya Koh Samui; Kamalaya Koh Samui; Kamalaya Koh Samui
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