Lewis Hamilton Felt Rested in Singapore. His Sleep Score Said 40%

Lewis Hamilton felt rested in Singapore, but his sleep score kept coming back at about 40%. "Even if I sleep and I feel like I have slept well, my sleep score is coming out like 40 per cent, and I'm really worried," he told reporters, including RacingNews365, before the 2026 Singapore Grand Prix.

The short answer: a low score after a night that felt fine is not proof you slept badly. Sleep trackers are good at spotting sleep and much weaker at spotting wake and sleep stages. And the score itself can change how tired you feel the next day.

If you wear a ring, watch or band in Singapore, here is how to read that number without letting it run your morning.

What did Hamilton actually say about his sleep?

He was talking about the unusual Singapore race week. F1 teams and drivers stay on European time for the night race, which means going to bed around three or four in the morning and sleeping through daylight behind blackout blinds.

"My Whoop page is definitely going to be affected by this week," he said, adding that getting efficient sleep is "tough to do here." He also named "the lighting and everything, and what you eat and when you eat" as things that affect him.

So the score was reacting to a strange schedule. Hamilton's own sense of how he slept said something different.

How accurate are sleep trackers, really?

Better than many people think at one job, and worse at another.

A 2021 study in the journal Sleep tested seven consumer sleep trackers against polysomnography, the lab standard that records brain waves. Thirty four healthy young adults slept in the lab for three nights, including one night designed to be disrupted.

| What the devices were measuring | What the study found | |---|---| | Detecting sleep (sensitivity) | High, 0.93 or above for all devices | | Detecting wake (specificity) | Low to medium, 0.18 to 0.54 | | Sleep stages (light, deep, REM) | Inconsistent, mixed results | | Disrupted nights | Devices tended to perform worse |

That pattern matters. The nights you most want to understand, the restless and broken ones, are the nights trackers read least well.

Most of the devices did as well as or better than research actigraphy at sorting sleep from wake. Stage breakdowns are where you should hold the number loosely.

Can a bad sleep score make you feel worse?

It looks like it can.

1. The sham feedback study. In a 2018 Journal of Sleep Research experiment, 63 people with insomnia wore an actigraphy watch and got fake next-morning feedback. Those told they slept poorly reported lower alertness (effect size d = 0.79) and more sleepiness and fatigue (d = 0.55) by evening than those told they slept well. Their reaction-time scores barely differed (d = 0.12).
2. The placebo sleep study. In two studies with 164 participants published in 2014, people were randomly told they had spent either 28.7% or 16.2% of their sleep in REM. The assigned number, not how they said they slept, predicted their scores on two attention and verbal tests.

The authors of the 2018 study wrote that the findings have important implications for wearables that claim to measure "objective" sleep but may be inaccurate compared with lab measurement.

In plain words: the number on your phone can shape your day, even when it is wrong.

What is orthosomnia?

It is a name sleep clinicians gave to an unhealthy chase for perfect tracker data.

A 2017 paper in the Journal of Clinical Sleep Medicine described patients seeking treatment for problems they had diagnosed from their tracker, such as "light" or "restless" sleep. To some of them, tracker data felt more true to their experience than validated lab tests. The authors suggested building trackers into standard insomnia therapy rather than ignoring them.

Hamilton thinking about his score "every day" is a mild, very human version of this. Most of us have done it.

Does Singapore's heat show up in your score?

Yes, and here the trackers are on solid ground, because they are measuring when you fall asleep and wake up.

A 2022 study in One Earth linked more than 7 million sleep records from 47,628 people with tracker wristbands in 68 countries to local weather. Warmer nights shortened sleep, mostly by delaying sleep onset. On nights above 30°C, people slept 14.08 minutes less than on nights with the least temperature linked sleep loss. People in hotter regions lost more sleep per degree of warming, which the authors said suggests limited adaptation.

That is relevant if you sleep in Singapore. A Straits Times report on Project HEATS found the average Singapore bedroom sat at about 28.4°C at night. We looked at what that does to bedding in our 28.4°C bedroom post.

How should you read your sleep score instead?

1. Look at the week, not the morning. One low score after a late night, a long flight or a hot room is noise. A trend over seven nights is a signal.
2. Check timing first. Hamilton's score dropped with a 3am bedtime. A shifted schedule can drag a score down even if total sleep looks fine.
3. Trust duration and timing more than stages. Those are what devices measure best.
4. Ask how you feel before you open the app. Note it, then compare. If you feel fine and function fine, that counts.
5. Change one thing at a time. If heat is the suspect, try one change for a week, like a timed fan, a breathable cotton sheet, a cooling blanket or a lighter cooling weighted blanket, and watch the trend. We compared fabric feel against measured data in our cooling mattress cover post.

If you do use a weighted blanket in a warm room, fabric and fill matter more than weight alone. Our specifications page lists what goes into ours.

A tracker is not a diagnosis. If you snore loudly, wake gasping, or feel sleepy through the day for weeks no matter what the app says, talk to a doctor.

So when you wake up feeling good and the app says 40%, which one are you going to believe?

Sources

• RacingNews365. Lewis Hamilton airs unusual 'Whoop' fear in unique F1 challenge, 9 October 2026. https://racingnews365.com/lewis-hamilton-airs-unusual-whoop-fear-in-unique-f1-challenge
• Formula 1. How drivers prepare for the Singapore Grand Prix, the toughest race on the calendar. https://www.formula1.com/en/latest/article/surviving-and-thriving-in-singapore-how-drivers-prepare-for-the-toughest.5WK0nvwo8wQWmpT4LZgFJB
• Chinoy ED, Cuellar JA, Huwa KE et al. Performance of seven consumer sleep-tracking devices compared with polysomnography. Sleep, 2021. https://doi.org/10.1093/sleep/zsaa291
• Gavriloff D, Sheaves B, Juss A et al. Sham sleep feedback delivered via actigraphy biases daytime symptom reports in people with insomnia. Journal of Sleep Research, 2018. https://doi.org/10.1111/jsr.12726
• Draganich C, Erdal K. Placebo sleep affects cognitive functioning. Journal of Experimental Psychology: Learning, Memory, and Cognition, 2014. https://doi.org/10.1037/a0035546
• Baron KG, Abbott S, Jao N et al. Orthosomnia: Are some patients taking the quantified self too far? Journal of Clinical Sleep Medicine, 2017. https://doi.org/10.5664/jcsm.6472
• Minor K, Bjerre-Nielsen A, Jonasdottir SS et al. Rising temperatures erode human sleep globally. One Earth, 2022. https://doi.org/10.1016/j.oneear.2022.04.008
• The Straits Times. What's the temperature in the bedroom in Singapore? A muggy 28 deg C, 25 June 2026. https://www.straitstimes.com/singapore/environment/whats-the-temperature-in-the-bedroom-in-spore-a-muggy-28-deg-c-says-new-study-on-residents