Meaning trap
brighten up
become or make happier
To start to look or feel happier, or to make someone feel happier.
Don't mix these meanings
Same phrase, different job.
To start to look or feel happier, or to make someone feel happier.
Another meaning of 'brighten up' is 'make brighter or happier'; compare the examples to keep the meanings separate.
Hear it in context
Notice where the phrase sounds natural.
She really brightened up when she saw her friends at the party.
Honestly, a quick chat with a friend always brightens me up when I've had a long day.
Fix the pattern
One small grammar move makes it sound right.
Not: She brightened up herself when she heard.
Say: She brightened up when she heard.
In this sense 'brighten up' is intransitive — no object. (Cheering someone else is 'brighten up their day'.)
Which sounds natural?
Tap the one a native speaker would say.
'Brighten up' is the natural verb for a mood lifting (or weather clearing); the formal version is stilted.
Build natural chunks
Words that usually travel with it.
brighten up (become happier)
- the weather
- her face
- later
- no end
Don't confuse it
Related
Other meanings and phrases to compare.
- brighten up (make a place cheerful) — Another meaning of 'brighten up' is 'make brighter or happier'; compare the examples to keep the meanings separate.