Sleep Calculator - Cat in bed

Sleep Calculator: How Much Sleep Do I Really Need?

Sleep Calculator

What time will you close your eyes and try to sleep?


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Just like fingerprints, our sleep needs are unique to each of us. While it's usually recommended that adults aim for at least seven hours of sleep, some may find their personal paradise in eight or nine hours, and some might only need five or six. 

1. Tailored sleep needs

Sleep Calculator - Woman in bed

Let's forget the one-size-fits-all approach and really try to understand our sleep needs. Track your sleep hours and pay attention to what it takes for you to rise and shine consistently refreshed.

Did you know? People over 40 may need 30 minutes less or more sleep than they did in early adulthood. – University College London 

Setting a regular bedtime and wake-up time, even on weekends, is like planting the seeds of restful slumber. But how do you determine the ideal time for you to sign off for the day?

Working out your bedtime 

Calculate your perfect bedtime by working backwards from your unprompted wake-up time – in other words, when you’re on a day off – making sure to account for the time it takes you to drift off to sleep and any occasional nighttime awakenings. 

Then, it’s a case of subtracting the hours’ sleep you need from your wake-up time. So, for example, if you need to be up most days at 6:30am and your body demands eight hours sleep, then you should be nodding off at about 10:30pm. 

But we get it: life can sometimes throw curveballs your way, and sticking to the exact same schedule every day isn’t realistic. In such cases, your goal should be to maintain as much consistency as possible with your bedtime and wake time. Think of it as providing your body with a rough schedule, so it knows when to expect that warm embrace of sleep.

For an added nudge in the right direction, set a reminder for yourself when it's time to start winding down in the evening. It's a subtle cue to switch gears, calm your mind and prepare for a night of rejuvenating rest. And remember the 3-2-1 rule: no food three hours before bed; no liquids two hours before bed; and no screens one hour before bed.

If you’re unsure about how much sleep you need, and how to wake up at the end of a sleep cycle rather than the middle of one (more on that later), use our handy calculator above to give you a better idea

2. How much sleep to aim for 

How much sleep do I need? Sleep Calculator

Achieving a refreshing start to your day isn't about a precise number of sleep minutes or hours, but rather finding the right range based on your age and lifestyle. Take a look at these guidelines to enhance daytime alertness:

Newborns (0-3 months): Babies need 14 to 17 hours of sleep, including daytime naps, as uninterrupted nights are rare during this stage.

Older Infants (4-11 months): Aim for about 12 to 15 hours of sleep daily to support their growth and development.

Toddlers (1-2 years): The goal should be 11 to 14 hours of sleep to ensure their well-being during these formative years.

Preschoolers (3-5 years): The optimum amount is 10 to 13 hours of sleep each night.

School-age Kids (6-13 years): Aim for nine to 11 hours, fostering healthy growth and cognitive function.

Teenagers (14-17 years): Navigate the teenage years with eight to 10 hours of nightly sleep, acknowledging the slight decrease in sleep needs.

Adults (18-64 years): Maintain a balanced sleep routine with seven to nine hours per night to promote overall well-being and cognitive function.

Older Adults (65+ years): Tweak your sleep duration to seven to eight hours, recognising potential changes in sleep patterns with age.

By aligning your sleep habits with these age-appropriate recommendations, you can optimise your rest and enhance your alertness throughout the day. Here’s a handy graph from the National Sleep Foundation: 

Sleep Calculator - Sleep Foundation

3. Understanding Sleep Cycles 

Before we delve into why sleep is so crucial to almost every aspect of our lives, let’s take a look at how sleep works. 

The ‘sleep cycle’ is an orchestrated series of distinct phases that repeat throughout the night. Understanding the stages of sleep provides insight into how sleep works its restorative magic.

Stage 1 - “Light sleep”

You are drifting to sleep as brain wave activity starts to slow. Muscles relax while you remain somewhat aware of your environment. Ever twitch or jolt? This will almost always be during the light sleep phase. 

Stage 2 - “True sleep”

This stage occupies about half of total sleep time. Brain wave frequency continues declining with occasional bursts of activity. Body temperature drops and heart rate slows as you detach from surroundings.

Stages 3 & 4 - “Deep sleep”

The deepest, most restorative sleep. Breathing is slow and blood pressure low. Blood supply increases to muscles and tissues, restoring the body. Waking is very difficult during deep sleep.

REM sleep

Yep, this level of sleep is so good the band named themselves after it. Vivid dreaming occurs during rapid eye movement (REM) sleep. Nerve pathways in the brain that prevent muscles from moving are active during REM sleep to stop us acting out dreams. Heart rate, breathing and brain activity increase to levels seen while awake. Memory consolidation happens in REM sleep.

The sleep cycle repeats through light sleep, deep sleep and REM over 90-minute intervals throughout the night. Quality sleep means ample time in each critical phase, and you want to try to avoid waking up mid-sleep cycle, so consider this when working out how many hours you need. 

4. Impact of Sleep Deprivation

Impact of sleep deprivation - Sleep Calculator

Sleep plays a vital role in nearly every aspect of our physical, mental and emotional health. That's why it's so critical to make sleep a priority and invest time into improving your sleep habits. After all, your health is your biggest wealth! 

Physical health

Quality sleep is essential for physical health and proper immune function. Chronic lack of sleep raises risks for numerous conditions including heart disease, high blood pressure, diabetes, obesity and stroke. Deep sleep is when the body releases growth hormones needed for muscle repair, tissue growth and cellular regeneration.

Mental health

Sleep is crucial for cognitive performance, concentration, memory and productivity. Insufficient sleep impairs decision making, innovation, focus and reaction time. The brain uses sleep to clear out neurotoxins that accumulate during waking hours. Ongoing poor sleep is linked to anxiety, depression and other mental health issues.

Quality of life

Consistently not getting enough sleep negatively impacts mood, relationships, performance at school and work, appearance, libido, accident risk and overall wellbeing. People who sleep better report higher life satisfaction and happiness. Protecting sleep enhances joy and reduces irritability.


Studies show that short and long sleep durations are associated with increased mortality risk and shorter lifespan. A good night's sleep strengthens your health, optimises immune function and helps prevent disease. Prioritising healthy sleep may be one key to longevity.

As you can see, sleep affects virtually every system and function in the mind and body. Treat sleep as a precious resource for health, happiness and a fulfilling life. Your future self will thank you.

Did you know? Over a third (34%) of Brits believe they have physical or mental health problems linked to poor sleep. – Direct Line 

It all goes to show that the importance of the consistent right amount of sleep should not be underestimated. 

If you’re still unsure about how much sleep you need, and how to wake up at the end of a sleep cycle rather than the middle of one, use our handy calculator at the beginning of this article to give you a better idea.

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