Adam Peaty hopes kickstarting Great Britain's gold medal rush at Tokyo 2020 can lift the mood of the nation after revealing he has spent every day of the last 18 months "almost in the dark".

Peaty became the first British swimmer to successfully defend an Olympic title after roaring to victory in the men's 100 metres breaststroke final in 57.37 seconds, the fifth fastest time in the history of the event, with runner-up Arno Kamminga a distant 0.63secs adrift.

His coronation has seemed inevitable for a while as not only is he unbeaten in major competitions over the distance in seven years, his personal best of 56.88s is almost a second quicker in the event than anyone else in history.

But the 26-year-old, who was followed to gold by diving duo Tom Daley and Matty Lee and cyclist Tom Pidcock on a memorable Monday for Team GB, admitted the Covid-19 pandemic has brought its own unique challenges.

"Sport has an amazing power to inspire people and an amazing motivation for people this morning getting up in Britain who have been through a tough time," said Peaty, who was congratulated on Twitter by Prime Minister Boris Johnson.

"These last 18 months, every single day has almost been in the dark. Covid has taken a lot of fun out of things. We have been at home a long time.

"All these days we spend, if you put into a percentage, it's 99.9 per cent in the dark, searching for a bit of light, then the 0.01 per cent was that performance. That's why I put that amount of investment into what I do.

"Hopefully this is a catalyst for not only Team GB but also the people back home to go to another gear and say we've been through a tough time, there is a lot of complaining, a lot of excuses, just negative things, but you've got to switch your mindset and that's exactly what we had to do."

Peaty, who swore twice on the BBC in an emotional poolside interview in the moments after writing his name into the history books, became a first-time father last September when partner Eiri Munro gave birth to baby boy George.

He knows a single-minded determination to back up his Rio 2016 triumph has meant a lot of time away from his young family, and while he has designs on going for a hat-trick of golds at Paris 2024, he is not committing to anything.

"In sport very simply, as soon as I stop having fun, I'll stop," he added. "I'm still having fun, a lot of fun with my boy and at home, and in my normal life too. Such a big decision is a family decision.

"It's not just me being a selfish athlete – because we have to be selfish – but we will have that conversation when we get home. We are targeting Paris. Anything after that is a bonus, really.

"Being a father now, my priorities have changed. I know these guys are going to be racing in the ISL (International Swimming League) in a few weeks' time. I probably won't be.

"The amount of time that has been taken away from me with my partner and my boy – he doesn't know it – but I want to make that time up. These are moments we will never get back."

Italy's Nicolo Martinenghi collected bronze in a time of 58.33s as Britain's James Wilby missed out on a podium position, settling for fifth as he clocked 58.96s, in a race where Peaty showed his enduring class from the off.

He had established a handy lead by the turn which he never threatened to relinquish as his stranglehold over this discipline continued. But he insisted he does not take his supremacy over the rest of the field for granted.

"No-one's invincible, everyone can be beaten," a visibly relieved Peaty said afterwards. "I'm a firm believer in that. If I didn't believe that I wouldn't have the world record. It's just really about setting no limits.

"That race was mine to lose. Everyone knew it. I was trying not to think it but I was trying to be as free as I can.

"It's a very very...a big relief. I'd put it simply: if you were looking for promotion and worked your a*** off for five years to get that promotion and then had to prove yourself in 57 seconds.

"Under that pressure a lot of people could fold. But I've shown, time and again, that I can perform when it matters and get faster through the rounds. That's what I do."