My Oura Ring helped me go from 6 to 7 hours sleep a night — and this Prime Day deal drops the 4th gen to its lowest price yet

I love my Oura Ring 5 but the Oura Ring 4 is still one of the greatest sleep trackers on the market — so I couldn't believe my eyes when I saw it drop to its all-time lowest price for Prime Day. The Oura Ring 4, now £189.05 (was £349) at Amazon UK, provides accurate sleep tracking wrapped up in a comfortable, stylish smart ring design.Before the 5th gen Oura Ring came along this summer, the Oura Ring 4 topped our best sleep trackers guide thanks to its advanced features and sleek build. The 5 might have had a slight upgrade but the Oura Ring 4 is still a top-rated tracker, now more so than ever thanks to this £159.95 discount.But October Prime Day is only a two-day event (unlike the four-day Prime Day event in June, when the Oura Ring 4 was £232), so I wouldn't deliberate on nabbing the best Amazon Prime Day sleep deal I've seen this year.Oura Ring 4 vs Oura Ring 5: What's the difference? (Image credit: Future)While the rock-bottom price of the Oura Ring 4 is a huge draw, as is our glowing Oura Ring 4 review, you may be worried that as a previous generation design it's inferior to the Oura Ring 5.While it's true that the new model is slimmer and lighter than the Oura Ring 4 — and has a broader ranger of sizes — they both boast the same features.Both have super-accurate sleep tracking, expertly reporting how long it takes you to fall asleep and your sleep stages. As for app features, you can find all the same key metrics and insights on both the 4th and 5th generations. Subscription fees are the same, too.The big differences to be aware of are a slightly shorter battery life (the Oura Ring 4 has up to 8 days of battery life while the 5th has up to 9 days), less powerful LEDs, and a thicker design.However, these differences aren't dealbreakers for me. The 4 still features the excellent metrics and advice that helped me go from six to seven hours of sleep a night — I can sacrifice a day of battery for the savings and the benefits.Smaller budget? Try this... Get instant access to breaking news, the hottest reviews, great deals and helpful tips.