Adam Levine
Adam Levine of Maroon 5 celebrated his 37th birthday on 18 March Kevin Winter/Getty Images for CBS Radio Inc.

Adam Levine celebrated his 37th birthday alone by spending the day in bed eating cake. The Maroon 5 frontman brought in his big day on 18 March and spent it reflecting on life.

"For my birthday yesterday I sat in bed all day with the shades drawn eating this cake completely alone," he wrote alongside an Instagram post of the half-eaten cake. "It might have been the best birthday I've ever had. I took time to reflect on so much and had a moment to genuinely appreciate the life that I have and the incredible people I have in it. I highly recommend taking at least one birthday in your life and keeping it to yourself. It f****n RULED. And that cake was GOOD."

The Animals singer may have decided to spend the day alone but he wasn't forgotten. His pregnant wife Behati Prinsloo sent him an adorable Instagram message on the special day. "Happy birthday to the love of my life," the Victoria's Secret model posted. "Everything is boring and meaningless without you!!! #BestHusband."

Happy birthday to the love of my life! Everything is boring and meaningless without you!!! 💋 #besthusband 🙇🏻

A photo posted by Behati Prinsloo Levine (@behatiprinsloo) on

The couple, who got married in 2014 in Mexico, we keen to start a family soon and back then Adam told E! News: "Yeah, we're gonna do it at some point in the not-so-distant-slash-undisclosed-slash-I-really-have-no-idea-big-question-mark future," he joked. "Is that ambiguous enough for you?" It was confirmed early March that the couple are now expecting their first child.

Maroon 5 is currently in Brazil and completed a concert in Sao Paolo on 19 March and another in Rio de Janeiro on 20 March.