Sleep has a number of critical functions and is essential for good
health and wellbeing. Lack of sleep has a profound impact on our brain’s ability to function. The cumulative impact of successive nights of poor sleep is significant. There is a strong relationship between sleep and physical and mental health. This is why taking steps to prevent sleep deprivation or poor sleep is so important.
Sleep occurs in a recurring cycle of 90 to 110 minutes and is divided into two categories: non-rapid eye movement (non-REM) and rapid eye movement (REM) sleep. REM sleep is so called because during this type of sleep, your eyes move rapidly from side to side behind your eyelids. During REM sleep, your brain activity increases, your pulse quickens, and you have dreams. REM sleep first takes place after you’ve been sleeping for around 90 minutes.
REM sleep is really important, as it is during this type of sleep that our brain processes and consolidates newly acquired information, and also actively forgets unimportant information.
Think of your mind as a busy office with stacks of papers and post-it notes everywhere. At night when we dream, this is the time when we tidy this office and sort out what we need to keep and remember, and what is less important and we can forget.
REM sleep is also when we dream and dreaming has an important function for our wellbeing. REM-sleep dreaming appears to take the painful sting out of difficult, even traumatic, emotional episodes experienced during the day, offering emotional resolution when you awake the next morning.
Dreams also allow us to act out things we can’t do in real life and is when we ‘emotionally vent’. When we are distressed we dream more because we need more of this ‘emotional venting’. And don’t worry if you think you don’t dream, you do, we just don’t remember almost all of our dreams.
In order to have a restful night’s sleep, you should establish good ‘Sleep Hygiene’. Sleep Hygiene refers to the ideal conditions for a good night’s sleep.
Good sleep hygiene includes:
Fixed times for going to bed and waking up – Once you establish a fixed routine, your body gets used to going to sleep and waking at certain times. Your regular bedtime will then become the critical time when your mind and body becomes tired and is ready for sleep.
Maintaining a comfortable sleeping environment – Your bedroom should be slightly cool (16-18 degrees) as the body temperature naturally lowers when preparing for sleep, so a cool room will help with this. You should also sleep in a room that is as dark as possible, to stimulate melatonin (a hormone that regulates sleep) to be released to help you feel relaxed and ready for sleep.
Avoid caffeine, nicotine and alcohol late at night – Caffeine, as can be expected, can disrupt sleep. Caffeine takes a long time to get out of our system, so it is a good idea not to drink caffeine after midday, to ensure it has been released from our system by the time we go to sleep. Some may think that a couple of glasses of wine before bed actually helps them get to sleep, but alcohol consumption actually blocks REM sleep, meaning that although you will be sleeping, you will get much less of the important, restorative REM sleep. Nicotine is also a stimulant so is best avoided late at night.
Fluid restriction 2 hours before bed – We benefit most from sleep that is uninterrupted but often our sleep is interrupted by having to get up and use the bathroom (especially as we age and our bladder sphincter muscles weaken). The simplest solution to avoid this is to make sure you are well hydrated during the day, and then restrict fluid intake in the 2 hours before bed, giving you time to empty your bladder before sleep.
Adults need between 7 to 9 hours of sleep a night but how much sleep works best for you is very individual, and your sleep requirements will vary with factors such as age and how active your lifestyle is. Some people will need more sleep and others less. You will most likely know how much sleep you need to feel at your best the next day, so respect this – needing 10 hours a night may be best for some people and doesn’t make you lazy! Alternatively you may need less sleep – but less than 6 hours is not a good idea as it is linked to a higher mortality risk.
Melatonin, also know as the sleep hormone, is produced by the pineal gland in our brains. Melatonin is responsible for regulating sleep and wakefulness. In the morning, the natural blue light emitted from the sun tells our brain that the day has begun and that it is time to feel awake and alert. After the sun sets and it becomes dark, the lack of blue and green light in our environment tells our brain that it’s time to wind down, so it releases melatonin, making us feel relaxed and sleepy and allowing us to obtain deep and restful sleep. However, using blue-light emitting devices such as smartphones and tablets before bed tricks the mind that it is morning, and so restricts the release of melatonin. Stopping using these devices at least an hour before bedtime can avoid this disruption.
Exposing ourselves to sunlight during the day can help us sleep at night. Sunlight stimulates the eye with light pressure, which in turn stimulates the production of melatonin. When it becomes dark at night, this melatonin is released, making us feel relaxed and sleepy and ready for bed. So it is a good idea to get outside as much as you can during sunlight hours.
Your mind should recognize your bed as a relaxing place for sleep and intimacy only. If you sit in bed and work, surf the Internet, or watch TV this is unlikely to be the case. Also, our memory can be ‘context dependant’. This means that our retrieval of memories is easier if we are in the same context and environment that we made the memory in. You have probably experienced this if you have ever returned to the home where you grew up, or a school that you used to attend. When you do this, memories of events that happened there came more readily to mind. So if you have sat on your bed during the day to complete a task or make a call that you find stressful, at night you are more likely to recall and think about this stressful episode as you are in the same environment (on your bed in your bedroom) that you made it in. However if your bed is used only for sleep, you can more easily switch off at night and put these memories out of your mind.
PHE has launched a sleep and recovery toolkit for all employers which consolidates the best evidence, employer practice and aligned with the best freely available resources.
Matthew Walker, a professor of neuroscience and psychology and the director of the Center for Human Sleep Science at the University of California, has written a science based book about sleep - Why We Sleep.