Newborns don’t have an established circadian rhythm; it isn’t established until they’re 2 to 3 months old. Infants tend to sleep in several phases throughout the day, taking naps from 2.5 to 4 hours at a time. By around 12 months, infants start sleeping more at night. At this point, they start to sleep more like adults in that there don’t move their bodies during REM (rapid eye movement) sleep, which is when people dream. Previous to 12 months, babies will move during REM sleep.

Recognising when school-age children aren’t sleeping enough can be difficult as tired kids tend to not slow down, they speed up. They’ll engage in behaviors that look like ADHD. This includes resisting going to bed at night, even though they’re tired.

Children with ADHD can cause sleep loss in children, as well as other issues such as sleep apnea (when people stop breathing for periods throughout the night). It was previously believed that sleep apnea only occurred in adults, but now the America Academy of Pediatrics recommends asking about and screening for sleep apnea in children.

According to the National Sleep Foundation, circadian rhythms shift after puberty, making teens want to go to bed after 11 pm and wake up later. With teenagers having the earliest start times, they are often getting up at 5 am to be at school by 7 am, which makes it rarer that a teen will get enough sleep. One study found that only 15 per cent of teens reported sleeping 8.5 hours per night.

Because teens are sleep-deprived during the week, they sleep more on the weekend, which can make the problem worse. One of the top recommendations from sleep experts is to fall asleep and wake up at the same time every day.

A problem that many teens share with adults is the use of back-lit devices late at night, which can prevent sleepers from getting quality sleep.

Adults tend to not get enough sleep for a list of reasons from too much stress to drinking to much coffee and looking at blue-light emitting devices within 90 minutes of going to bed. Inconsistent sleep schedules also contribute to a lack of sleep.

Women need on average 20 more minutes per night more than men, though some women need more than that. One theory as to why is because women multitask more than men and have busier schedules, which results in their brains using more energy and therefore needing more recuperation. Another possible reason is the monthly hormone cycle that occurs with menstruation.

Many adults aged 65 and older nap during the day because they don’t get enough quality sleep at night. One of the reasons they don’t sleep well is because of medical conditions such as restless legs syndrome. Many seniors also suffer from illnesses and take medications, both of which can disturb sleep.

Another common issue among seniors is that it takes them longer to go to sleep, with one study showing 13 per cent of men over 65 and 36 per cent of women taking more than 30 minutes to fall asleep.