Hotel lighting and the body clock: what guests notice, even when they don't know it

Hotels spend a great deal on beds, blackout curtains and quiet rooms, because a good night's sleep is the thing guests remember. Lighting usually gets less thought. It is chosen for how the room looks in the photographs. Yet light is the strongest signal the body clock responds to, and in a hotel room the guest's body clock is often under more strain than at any other time.

Why light matters more when you travel

Your body clock keeps time using light. Each day it uses the light you see, especially in the morning and evening, to stay in step with the outside world. That system works well when you stay in one place. When you travel across time zones, your clock is suddenly hours out of step with local time. That is jet lag, and light is the main thing that resets it.

Light at the right time helps the clock move the right way. Light at the wrong time can push it the wrong way and make the adjustment slower. A guest arriving late in the evening after a long-haul flight, then sitting under bright light until midnight, may be undoing the very thing they need. You can read more about how this works in our guide to circadian lighting.

What guests notice

Most guests could not tell you what the lighting in their room was like. But they notice the effects:

• Bright, cool light late at night. A room lit for a sharp photograph can feel stark at 11pm and make it harder to wind down.
• No gentle option. Many rooms have overhead lights and little else, so the choice is bright or dark.
• Light at night. A trip to the bathroom often means switching on a bright light, which can make it harder to get back to sleep.
• Dim mornings. Heavy curtains are good for sleep, but a dark room in the morning gives the body clock little to work with.

What good hotel lighting looks like

The answer is not more light or less light. It is the right light at the right time.

Morning. Brighter, crisper light helps guests wake and gives the body clock a clear morning signal. Opening curtains automatically, or bright light in the bathroom and breakfast areas, both help.

Daytime. Restaurants, lounges and meeting rooms benefit from bright, daylight-like conditions, especially in windowless spaces.

Evening. Warmer, softer light as the evening goes on, in the room, the corridors and the bar, so guests are not pushed later than they want to be.

Night. Low, warm guide lighting for the bathroom and the walk across the room, so a night-time trip does not mean switching on the full lights.

Many hotels can make a start with the controls and fittings they already have. Scenes that change through the day, and a proper night setting, cost far less than a refurbishment.

The traveller's body clock

Hotels already know a great deal about their guests: where they have come from, when they arrived and how long they are staying. In principle that is enough to know which way a guest's body clock needs to move and when light would help or hinder. That is one of the areas we are researching at Sensio BioLabs. We think lighting that adapts to the guest, not just to the time of day, is where hospitality is heading.

The same thinking applies at home when the clocks change, and in any building where people live and sleep. Our article on human-centric lighting looks at what buildings more widely tend to get wrong.

Questions to ask about your hotel's lighting

• Can guests set a soft, warm light in the evening without turning everything off?
• Is there a low night light route to the bathroom?
• Do the lights in corridors and public areas change through the day, or stay the same at 7am and 11pm?
• Do windowless spaces such as meeting rooms and gyms get bright, daylight-like light during the day?

This article is for general information and is not medical advice.