Our sleep needs change over the course of our lives, in keeping with our age and stage of development. How much sleep is enough? Here’s what the experts say.
0 – 3 months
Babies have high sleep needs due to the significant growth during these early years of life. Babies' sleep cycles are different too, as they spend more time in rapid eye movement (REM) sleep. This is linked to brain development, which is progressing at a rapid rate from birth to age 3 years; 90% of total brain development takes place during this period. REM sleep is a lighter sleep, closer to wakefulness in terms of brain activity. For this reason, babies are easily woken.
Their circadian rhythms are still developing, too. These factors help to explain why babies will generally wake every 3 – 4 hours during the first 6 weeks of life; combined with their need to feed regularly to fuel their growth. A newborn sleeps between 16 and 18 hours per day.
3 – 6 months
Babies of this age will sleep on average 13 - 15 hours per day. 8 - 10 hours will be at night, with the remainder taken in naps during the day. By age 6 months, babies have usually reduced their daytime naps from several to just two. 7pm – 8pm is a good bedtime for a baby of this age, and having set daily nap times is also advisable. Waking a baby at the same time each morning helps to reset their body clock and keep them in a good routine.
6 – 9 months
Babies at this age need about 14 hours of sleep over a 24-hour period. They will sleep about 7 hours at night and usually still have two naps during the day.
9 – 12 months
At this age, babies are often sleeping 11 – 12 hours a night and napping twice a day for about an hour at a time.
1 – 3 years
A toddler of this age sleeps between 10 – 12 hours per day. They will often have one daytime nap, for 1 – 2 hours.
3 – 5 years
A child of this age usually sleeps for 11 – 12 hours per night. They may have moved past the daytime nap stage, but still benefit from some quiet time in the afternoon.
School aged children (5 – 12 years)
School aged children need 10 – 11 hours of sleep each night. Sleep is critical for school students, as it affects their ability to concentrate during the day. Sleep deprivation can cause children to be irritable and hyperactive, behavioural problems which may impact on their interpersonal relationships as well as their learning and focus. One of the modern-day issues exacerbating childhood sleep deprivation is technology. Brightly lit laptops, TVs and handheld electronic devices used in the evenings can affect circadian rhythms, making it harder for children to fall asleep. Restricting the use of these devices after school is advisable, especially for two hours before bedtime.
Teenagers need 9 – 10 hours of sleep per night due to the demands of puberty on their bodies. At this time, changes in their circadian rhythms can make it hard for teens to go to sleep early in the evening. For many, 10 – 11pm is a natural bedtime, yet they have to wake up early for school. This can create a sleep debt. If your teen wants to sleep in on the weekend, chances are they need to rest. Even so, it’s better if they can keep to a regular sleep/wake schedule for the full 7 days.
For adults, 7 – 8 hours of sleep a night is generally considered optimal. Research conducted on more than 15,000 healthy women aged 70+ found that those who regularly underslept (5 hours or less) or overslept (9 hours or more) were more likely to experience memory problems later in life. The other causal factor identified was those whose sleep patterns changed by two hours or more per night, which had a comparable effect to under sleeping or oversleeping on memory. There is also evidence linking sleep disturbances to the onset of dementia and Alzheimer’s disease in the elderly. Risk factors include shift work and health conditions that create problems with sleep.