Precise time to go to bed if you want to wake up refreshed at 7am

Ever found yourself hitting the hay super early to ensure you're up for work, only to feel even more tired in the morning? This is because it's not just a case of more sleep meaning more energy.

It's more complicated than that, though thankfully, a "sleep calculator" has been devised by home decor site Hillarys, - allowing us to figure out our ideal bedtime with a simple click. Rather than just the quantity of sleep, it's all about sleep cycles, according to experts.

Waking up mid-cycle can leave you feeling groggy, regardless of how long you've been asleep. If you need to rise at 7am, aim to hit the hay at either 9.46pm or 11.16pm. For night owls who can't manage these times, 12.46am and 2.16am will also do the trick, according to

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The calculator takes into account the average 14 minutes it takes folks to naturally drift off, so don't worry about being tucked in by these times. For those needing to rise at 6am, consider bedtimes of 8.46pm, 10.16pm, 11.46pm or even 1.16am. And if 8am is your wake-up call? Aim for a bedtime of 10.46pm, 12.16am, 1.46am or 3.16am.

What are sleep cycles?

A sleep cycle is roughly 90 minutes long and includes five stages: four of non-rapid eye movement (NREM) sleep and one of rapid eye movement (REM) sleep. We progress from light sleep in Stage 1 to a very deep sleep in Stage 4, which makes it hard to wake someone up at this point – hence the grogginess if you're roused during this stage.

The fifth stage, REM sleep, is where most dreaming happens. If you want to nail the perfect wake-up time, say 6:35 am to catch your train and arrive on time for work, pop that into a sleep calculator for a tailored bedtime.

For a 6:35 am rise, you should hit the hay at 9:21 pm, 10:51 pm, 12:21 am, or 1:51 am. As per the Sleep Calculator website: "Getting a good night's sleep is about more than simply going to bed early – it's about waking up at the right time too." It adds: "Using a formula based on the body's natural rhythms, the Sleep Calculator will work out the best time for you to rise or go to sleep."

The idea is that we all sleep in about five or six cycles lasting around 90 minutes each. Waking up mid-cycle can make you feel grumpy and unrested the next day. The goal is to wake up between cycles to start your day feeling refreshed.