When Should I Wake Up? The Truth About How Much Sleep You Need

When should I wake up? The answer is so often simplified. If you use a sleep calculator it will quickly tell you to wake up either six, seven and a half, or nine hours after you fall sleep. This is based on waking up in between sleep cycles which is not necessarily wrong. But there is much more to it than that. First of all, we all have different sleep cycles depending on lifestyle and age. And if we only use sleep cycles to tell us when to wake up, there can never be one definitive answer. In this article we look a little deeper into the science behind sleep to answer your question: when should I wake up?

Just answer the question! When should I wake up? 

When should i wake up

Wondering when should I go to sleep?

Sleep Is Kind Of Important

Before we dive into sleep cycles and how much sleep we should all be getting, it’s important to understand why sleep is important. Sleep doesn’t just refresh us and make us more awake, it is a fundamental part of a life. It has a huge impact on not only our physical and mental health, but also on our overall quality of life.

Check out all the benefits of sleep.

While we sleep our body goes to work. It’s the time where we heal. Ever go for a run and then go to bed feeling sore? Chances are you felt less sore in the morning, and that’s because your muscles were repairing themselves while you slept. It’s not just those sore muscles that heal though. According to the National Heart, Lung and Blood Institute, your heart and blood vessels repair while you sleep. In fact if you are sleep deficient you have “an increased risk of heart disease, kidney disease, high blood pressure, diabetes, and stroke.”

Sleep also affects the strength of your immune system. If you are regularly depriving yourself of the shuteye you need, chances are your body will have less fighting power against infectious diseases.

Sleep not only affects your physical condition. It also impacts on your mental health in a big way. In a post on the U.S. Department of Health & Human Services website, the Director of the National Center on Sleep Disorders Research, Michael Twery, Ph.D. wrote “Resilience to stress, emotional regulation, and inter-personal relationships are impaired by sleep deficiency”. I know I always feel much more emotional after a bad sleep!

Not only does sleep affect your overall mood and judgement. According to the Division of Sleep Medicine at Harvard Medical School, it plays a critical role in memory and learning. Being tired due to insufficient sleep has an effect on your attention span and therefore your ability to absorb information. Anything that you learn throughout the day is consolidated while you sleep, making your shuteye essential for memory.

OK, Sleep's Pretty Important. So How Much Sleep Do I Need?

Well, there’s no definitive answer to this question. Everyone is different and has their own optimal sleep length. However in general, according to the American Psychological Association adults need approximately 8 hours of sleep a night. This will also vary with age. In 2015 a study by Hirshkowitz et al. was published in the Journal of the National Sleep Foundation. The study used a multidisciplinary expert panel to determine the optimal sleep lengths for a range of age groups. They found the following recommended sleep hour ranges per age:

    •  Teenager (14-17): 8 - 10 hours
    • Young adult (18-25): 7 - 9 hours
    • Adult (26-64): 7 - 9 hours
    • Older adult (>64): 7 -8 hours

Related post: How Many Hours of Sleep Do Teens Need

Sleep Cycles And How They Affect When You Should Wake Up

While we sleep our brain is going through phases or cycles. These are made up of two different types of sleep. The first you may have recognised on someone before. Have you ever seen someone’s eyes flicker while they sleep? This is the first type of sleep pattern and it’s called rapid-eye-movement. This is the part of sleep where you dream the most. The second type of sleep is non-rapid-eye-movement and it’s further divided into three stages (N1, N2, and N3) which are characterised by increasing depths of sleep. N3 is the deepest stage of sleep.

During a normal sleep you alternate between rapid-eye-movement and non-rapid-eye-movement. Each alternation is one sleep cycle and the lengths of these will vary. According to the Division of Sleep Medicine at Harvard Medical School, the first cycle generally lasts 70 to 100 minutes and the remaining cycles average around 90 to 120 minutes. The structure of each cycle will also change. At the start of your sleep, you spend more time in non-rapid-eye-movement. This changes as your sleep progresses. With each sleep cycle you spend less time in N3 and spend increasing time in rapid-eye-movement sleep.

Your age will impact heavily on your sleep cycles. Children spend a large portion of their sleep in the deep N3 stage of non-rapid-eye-movement. This helps explain why children are deep sleepers compared to adults. With increasing age we spend less and less time in this N3 deep sleep phase during a typical night. The lengths of the sleep cycles also change with age. With children they typically last around 50 minutes and around 90 minutes with adults.

Age is not the only influence on our sleep cycles. Other factors include any recent sleep we may have had, our actions before sleep such as exercise, our emotional condition including stress levels and environmental factors like temperature and light.

More about sleep cycles.

So When Should I Wake Up?

This will vary according to factors including your age and lifestyle, and there is no definitive answer. However, assuming you are an adult with a healthy lifestyle and regular routine, you should aim to wake up 7.5 hours after falling asleep. According to sleep.org, its takes on average 10 to 20 minutes to fall asleep. So, set the alarm for 7 hours and 45 minutes from the time you go to bed.