How much sleep do you need? The risks of too much and too little sleep

When it comes to sleep, you may have heard uber-successful businessmen claiming they only rest for 4-5 hours a night or be familiar with Einstein’s 12-hour sleeping average. Confusingly, there are various claims on either side of the sleeping debate, making it hard to know what the perfect sleeping time is.

So, just how much sleep do you need to benefit physically and mentally? To help answer this, we’ve put together a guide to sleeping times. We explain why you need sleep, the risks of sleeping too much or too little and, most importantly, how much sleep you really need.

How much should we be sleeping?

For adults to function at their best, a study by experts at the Mayo Clinic found that the optimal time that we should be sleeping is an average of 7-8 hours. Sleeping for this amount of time helps keep your body rested and restored, as well as physically and mentally primed.

If you’re younger, this optimal sleep time increases. For example, 13-18 year olds should be sleeping for 9-10 hours and 1-2 year-olds should be sleeping for 12-16 hours a day. Sleeping for periods which do not fall inside these hours can cause several negative side effects (see the section below).

Also, when we talk about sleep, it’s important to make sure that this time with our head on the pillow is ‘quality sleeping time’. This will help advance the benefits of good sleep. If you want to learn more about getting quality sleep, then read our guide tips for better sleep, and your body will thank you.

The risks of too much or too little sleep

We know that 7-8 hours is the optimal time for sleep, but what happens if you’re consistently getting above or below this amount? One of the world’s most extensive studies into sleep found out.

The study was conducted by researchers from the University of Toronto and the University of Warwick, where they surveyed 117,000 participants from 21 countries about their bedtime and wake-up time. Those classed as having too much sleep were anyone who regularly slept for over 10 hours, and too little was anyone who slept under 6 hours, here are their results:

The risks of too much sleep

When it comes to those who were sleeping too much, there were a number of negative side effects. The ‘extreme sleepers’ in the study were, on average, physically slower, more prone to depression, and had higher rates of smoking and alcohol consumption. They also suffered more frequently from high blood pressure and chronic obstructive pulmonary disease (lung diseases).

Over the nearly eight-year study, the researchers found that over 7,300 people sleeping too much suffered cardiovascular events/disruptions. Tragically, 4,400 late sleepers participating in the study died, and a similar number experienced heart attacks or strokes.

The risks of too little sleep

When it comes to people not getting enough sleep (6 hours or less), the study found that they are more prone to accidents, suggesting that they aren't fully rested. The rate of cardiovascular events and deaths also appeared slightly higher among this group than among people who slept the optimum 7-8 hours.

One thing that the researchers found conclusive was that too little sleep definitely contributes to weight gain, an imbalance in hormone levels is to blame. Insufficient sleep leads to decreased production of the hormone leptin, responsible for curbing our hunger. In contrast, more ghrelin, an appetite-stimulating peptide, floods the stomach.

This hormonal disruption causes us to eat more, as supported by the study's findings of increased rates of overweight and diabetic individuals among short sleepers. Those sleeping a shorter amount also had mood irregularities, impaired cognitive function and a weaker immune system.

Why do we need sleep?

It might seem like a silly question, but knowing why we need sleep and its benefits can help motivate you to make a healthy sleeping pattern your priority.

The primary reason for our need for sleep lies in our brains. It tirelessly operates at full speed throughout the day, processing sensory information and complex data constantly.

After approximately 16 hours, the brain's capacity becomes exhausted. It craves sleep to allow its nerve cells to recover. During sleep, memory processes take place, temporarily storing information and impressions until they're reactivated when needed.

As well as weight management, a sleep of 7-8 hours also helps the body by aiding with the following:

• Restoration and rejuvenation
• Cognitive function and memory consolidation
• Energy conservation
• Hormonal regulation
• Immune function
• Emotional well-being and mental health
• Overall health and longevity

If you’re struggling with your sleep, then it might be worth trying out some different techniques. Check out our guide to breathing techniques for better sleep, as recommended by experts, and tips for better sleep. Both these guides will help with having better sleep and explain, in more depth, why a night of good sleep is so beneficial.

Best products for you to optimise your sleeping time

If your goal is to now be sleeping for 7-8 hours, there are some handy products which can help you. These can improve the time you’re asleep, help you fall asleep more easily, and track your sleeping pattern so you can stay on top of it.

• Lumie Sunrise Alarm, Currys, £42.99: The Lumie Sunrise Alarm features a sunrise setting that starts 30 minutes before your alarm time and slowly brightens to wake you up gently. Having an alarm means you can make sure you don’t oversleep. Check out our guide to the best alarm clocks for more.
• Simba Orbit Weighted Blanket, £169, Simba: Designed to help you drift off and stay there, the Simba Orbit Weighted blanket is made with nano-bead technology and breathable fabrics. With a 100% cotton machine washable cover, this weighted blanket aims to keep you cool and comforted all night long. For more information on weighted blankets, check out our guide to the best weighted blankets to help you sleep and relax, as recommended by sound sleepers.
• Magicteam Sleep Sound White Noise Machine, Amazon, £19.99: This portable, adaptable white noise machine offers 40 different sounds, 32 volume level options and three timer settings. White noise has long been used as an aid to sleep, with studies showing it has the ability to help people fall asleep up to 38% faster. Check out our guide to the best white noise machines for more choices and information.
• Fitbit Inspire 2 Health & Fitness Tracker, Amazon, £44: Fitbit’s Inspire 2 is a great basic tracker for anyone on a tight budget. It has heart rate monitoring capabilities and sleep tracking so that you can review and evaluate your sleep. It also tells you the quality of your sleep and how many times you woke up. Check out our guide to the best fitness trackers for more sleep-tracking devices.

If you want more expert tips and recommendations, check out our page on sleep, which includes guides on breathing exercises for a better sleep, the best eye masks for sleeping, the best white noise machines and the best bed sheets according to experts.