First impressions form in 0.1 seconds. And sleep loss shows on your face

4 min read

Before meeting someone new, you think about what to wear and what to say. But the other person probably forms their impression of you before you even start talking.

And the face seen in that instant changed with the previous night's sleep. In this article, I check the research on how fast first impressions form and whether sleep loss shows on your face, down to how the experiments were done.

Impressions of a face formed in 0.1 seconds

American psychologists showed people photos of strangers' faces for 0.1, 0.5, or 1 second, and asked them to judge attractiveness, likability, trustworthiness, competence, and aggressiveness [1].

Those judgments closely matched judgments made with no time limit, even at 0.1 seconds. Longer viewing didn't change the judgments much; what changed was people's confidence in them.

Trustworthiness in particular showed an especially high match between 0.1-second and unhurried judgments.

Faces after a sleepless night looked less attractive

So how much does that face change with sleep?

In a Swedish study, 23 people aged 18 to 31 were photographed under the same conditions twice: after a normal night's sleep, and after 31 hours without sleep [2]. When the photos were shown to 65 raters who knew nothing about the study, the sleep-deprived faces were rated as less healthy, less attractive, and more tired.

The people were the same. The only thing that changed was whether they had slept the night before.

Where on the face sleep loss shows

Another study by the same group looked at what looks different in sleep-deprived faces [3]. The raters more often saw these features in sleep-deprived faces:

• Droopier eyelids
• Red, swollen eyes
• Darker circles under the eyes
• Paler skin, more visible wrinkles and fine lines
• Downturned corners of the mouth

Sleep-deprived faces also looked sadder. All of this is the "face" information other people read in 0.1 seconds.

Even two nights of short sleep made people less sought out

The effect showed up even without anything as extreme as an all-nighter. In an experiment where sleep was cut to four hours for two nights in a row, faces after short sleep looked less attractive, less healthy, and sleepier than after enough sleep [4].

On top of that, raters were less willing to "socialize with" the people in the sleep-restricted photos.

How far we can take this

That said, each of these studies involved only a few dozen participants. They were experiments rating photos, so we don't know how much impressions change when you meet in person. And the research on sleep loss focused mainly on young adults.

Still, the finding that "sleep-deprived faces tend to look tired and less attractive to others" lined up in the same direction across separate experiments.

Summary

• Impressions of a face after 0.1 seconds closely matched impressions formed with more time
• Faces after 31 hours without sleep looked less healthy, less attractive, and more tired
• Sleep-deprived faces tended to show droopy eyelids, red eyes, darker circles, pale skin, and a downturned mouth
• Even two nights of four-hour sleep made faces look less attractive and made others less willing to spend time with them

The night before meeting someone important, secure your sleep before you pick your clothes. If noise or light makes your sleep shallow, see how to choose earplugs and an eye mask. Whether you can make it up with weekend lie-ins is in the catch-up sleep article.