"So many different things can trigger it," Tom told Metro. "Being in the music industry comes with highs and lows and if you struggle with depression, the extremes of these emotions can be heightened.
"It's been difficult in the past but the best thing I ever did was get help for it. I've been on medication for two years.
"People can be cynical about celebrities talking about it, but, hopefully, if someone hears about my experiences and gets help, then it's worthwhile talking about it.
"It's extremely common, anyone can be affected by it. It's nothing to be ashamed of and help is available."
The 28-year-old singer added that he first started displaying symptoms of depression when he was at school, but didn't know what it was. It was only after watching Stephen Fry's 2006 documentary, The Secret Life Of The Manic Depressive, that Tom realised that he suffered from the mental health disorder.
At the time, Tom was living and working with his fellow McFly bandmates, Danny Jones, Harry Judd and Dougie Poynter, who also went through "a tough time".
"With bipolar or manic depression you go through cycles and mine were quite recognisable," he said. "It coincided with what we were doing with writing and promotion. There was a lot going on.
"Other bandmates were also having a tough time. We lived together at the time, so that wasn't very good for our mental states."
Earlier this month McFly, who are celebrating their ten year anniversary, announced that they were joining forces with two members of Busted, James Bourne and Matt Willis, to form the supergroup McBusted.
The two pop bands first toured together almost a decade ago and will be performing their hit classics on a UK tour in April and May 2014.