Sleep is essential for good health and optimal physical and mental performance. Just go without sleep for a day or two to learn just how important sleep really is! However, a lot of us get by on much less sleep than we should. Studies suggest that one-third of adults and two-thirds of students sleep less than eight hours per night. When life gets busy, sleep is often the first thing to be sacrificed.
Getting too little sleep can have a massive impact on how you feel, not just physically but mentally too. Lack of sleep is linked to weight gain, numerous diseases, increased risk of depression and anxiety, and could even cause premature death. Lack of sleep is a leading cause of serious and fatal accidents.
But how much sleep do you actually need? That’s a tricky question to answer. Even scientific studies cannot pinpoint the exact amount of sleep you need to be healthy.
This is because several factors determine how much sleep you need, and every individual has unique needs and preferences.
Sleep needs according to your age
The amount of sleep you need can be affected by your age. Babies and young adults who are still growing and developing need more sleep. In contrast, more sedentary older people often need less. While the following chart shows how sleep requirements vary between the ages, it’s important to remember that these are very general guidelines. There are always exceptions who need more or less sleep.
- Newborns (0–3 months): 14–17 hours
- Infants (4–11 months): 12–15 hours
- Toddlers (1–2 years): 11–14 hours
- Preschoolers (3–5 years): 10–13 hours
- School children (6–13 years): 9–11 hours
- Teenagers (14–17 years): 8–10 hours
- Adults (18–64 years): 7–9 hours
- Older adults (65+): 7–8 hours
Studies have revealed that there are specific genetic mutations that can affect how much sleep you need per night. Other mutations affect at what time of day you prefer to sleep. This helps explain why some people are especially suited to nightshifts, while other people are not. This is called your chronotype. Average chronotypes are more active during the day, and less active at night. However, some people are “night owls,” and the reverse is true.
Genetic mutations may also dictate whether you are a sound sleeper or one of those unlucky people who toss and turn all night.
Because of genetic differences, some people only need six or so hours of sleep per night. In contrast, others require eight, nine, or even ten hours. It is essential to pay attention to how the amount of sleep you get affects how you feel and perform, adjusting the amount of sleep you get per night according to your genetic makeup.
Sleep quality versus sleep duration
Sleep quality refers to how deeply you sleep. If you sleep soundly, six hours of sleep can be very restorative. However, if you toss and turn all night, you may still feel tired after even eight hours of sleep.
Sleep quality can be affected by several things, including:
- Sleep apnea
- Levels of mental and physical activity
When determining how much sleep you need, it is important to consider how well you sleep. If you are a deep sleeper, you may be able to get by on less. In contrast, if you are a light sleeper, you may need more hours in bed to accumulate enough sleep and may even benefit from siestas and naps.
So, how much sleep do you really need?
Most people think that eight hours is the optimal amount of sleep per night. The reason for this belief is obvious; it’s right in the middle of the 7-9 hours that most sleep experts recommend. There are always outliers who only need six hours, or must get ten, but 7-9 hours seems to be a good average.
Remember also that, just because you can get by on only six hours per night doesn’t mean that you should. It is possible to get used to less sleep, but doing so could affect your mental and physical performance and your long-term health too.
It’s also impossible to repay a sleep debt just by having a lie-in at the weekends. The damage caused by lack of sleep is all-but instantaneous. You might feel more rested after a weekend lie-in, but it won’t undo the effects of getting too little sleep during the week. Ideally, you should get the same amount of sleep each and every night.
If you get up in the morning and feel wide awake and energized all day, you are probably getting enough sleep. However, if getting up is a struggle, you feel sluggish all day, or feel the need to take frequent naps, you probably need more sleep per night. Adjust your sleep duration according to your personal needs.
Too little sleep can have a profound effect on your mental and physical performance and health. You can get by on less sleep than you need, but that doesn’t mean you should. Most experts agree that adults need 7-9 hours of sleep per night, but factors like genetics, sleep quality, and age all affect how much you really need. Adjust your sleep duration to ensure you are getting the right amount for your personal circumstances. If you feel tired all the time, you probably need to go to bed earlier.
1. PubMed: Prioritizing Sleep Health: Public Health Policy Recommendations
2. PubMed: Human genetics and sleep behavior