Sleep is essential to every process in the human body in some way and is incredibly restorative. One study in mice has shown that during sleep the space between the their brain cells increased by 60% flushing cerebrospinal fluid in and washing toxins out to the liver for detoxification. This process has since been labelled the glymphatic process.
The two hormones melatonin and cortisol stay in balance to help you sleep at night and wake naturally in the morning. Melatonin is the hormone that helps us fall asleep. It’s usually first produced between 9 and 10pm under dim light conditions resulting in an energy drop until 6am when your circadian rhythm is reset by light which sends signals to your brain to stop it producing melatonin, and instead produce a spike of cortisol during the morning to wake you up. Your cortisol level slowly drops during the day until melatonin is once again produced in the evening to leave you feeling sleepy again. This 24 hour cycle is your circadian rhythm.
Your body clock is most responsive to light between 6am and 8.30am. Because light can reset your circadian rhythm, artificial exposure to light such as a laptop or tablet for just 1 hour at night can reduce your melatonin to daytime levels. And only 2 hours of iPad use at maximum brightness can suppresses your normal nighttime melatonin release and disrupt your sleep pattern. Blue light is particularly effective at keeping you awake. Beware of your smart devices as most screens emit blue light. To stimulate your bodies natural melatonin production at night, avoid electronic screens in the two hours before bed, use dim lights in the house and, if you sleep in a room near outside lights, invest in some quality black out blinds to keep out the light whilst you sleep.
Your body also takes the cue to become drowsy from your body temperature which, in the absence of modern heating, would drop as the sun went down. Late night exercise can increase your core body temperature so it can take longer to get to sleep. Try either a cold shower before bed or a hot shower immediately followed by a period of rapid cooling to help precipitate sleep.
Circadian Rhythm –
If waking in the morning leaves you feeling drowsy for an hour or so there are a couple of great ways to get round it. A single sleep cycle (from light, through deep and back to light sleep) takes 90 minutes. You can use this to plan what time you need to go to sleep. Waking up at the end of a sleep cycle when you are in light sleep minimises that drowsy feeling. If you need to get up at 7am plan to be asleep by either 10 pm or 11:30 pm resulting in either 5 or 6 full sleep cycles, this way you will be in light sleep at the end of the cycle when your alarm goes off.
An increase in light is the natural way to wake and if you don’t have the luxury of naturally waking up to the rising sun you can create an artificial dawn which can reduce the feeling of drowsiness you experience. Using an alarm clock such as the Philips Wake Up Alarm Clock results in a slowly intensifying light until the clocks alarm sounds. The reduction in drowsiness can be explained by rising skin temperature and the amount of wakefulness during the 30 minutes prior to your alarm going off.
So these are great ways to get to sleep and wake up but how long should you actually spend asleep? Most people require between 5 and 6 sleep cycles – 7.5 or 9 hours sleep. But be aware that the most beneficial hormone secretions and recovery occur when sleeping between 10pm and 2am. So it’s at your advantage to go to sleep early and wake up early, rather than stay up late, even if you can still fit 5 sleep cycles in before waking.
So, apart from sending us to sleep every night, why is melatonin so important? Melatonin improves immune system function, decreases the risk of osteoporosis and plaques in the brain (associated with Alzheimer’s), alleviates migraines and other pain, improves thyroid function, insulin sensitivity and helps with weight reduction. It also decreases blood pressure and the risk of a heart attack and stroke.
Melatonin also decreases the proliferation of cancer cells and tumour growth and enhances DNA protection from free radicals. Scarily, shift workers who naturally suffer from sleep deprivation on a regular basis HOW MUCH?? have a 60% increase in breast cancer and 35% increase in colorectal cancer. And it’s not just shift workers that suffer, office workers with no access to windows got 173% less exposure to light, and on average, sleep 45 minutes less per night.
You might think that losing 45 minutes of sleep a night is no big deal but sleep deprivation decreases melatonin levels and even a small reduction can have dramatic effects. There is a 5% increase in heart attack rates for three weeks after the clocks go forward and we experience the loss of only one hours sleep (an effect not seen when the clocks go back). So you can see just how important exposure to light during the day and avoidance of light at night, coupled with 7.5 to 9 hours sleep really is.
Shift work –
So if you need to do shift work, how can you reduce it’s harmful effects?
- Night shifts should be as short as possible.
- The number of consecutive night shifts should be minimised.
- Rotating shifts should be in a delay direction – morning to evening to night.
- As much time off as possible should be given after nights.
Sleep is an important part of controlling your appetite, the way you eat and how many calories you store. Your brain is a very hungry organ. Although it only accounts for 2% of your body weight, it consumes 20% of your energy. But after 24 hours of sleep deprivation there is a 6% decrease in glucose reaching the brain. When it’s sleep deprived your body cannot extract the glucose from the bloodstream as effectively as it does normally. The parietal and frontal lobes of your brain loose 12-14% of their glucose supply. These are the lobes that are associated with self control. Less glucose to these areas results in a loss of self control and leaves you tending to eat more. Sleep deprivation also increases activity in the amygdala – an area associated with the motivation to eat.
Losing sleep also affects the hormones which control your appetite. A study at the University of Chicago showed that getting 4 hours of sleep for 2 nights resulted in a 28% increase in grehlin (the hormone that makes you hungry) and 18% decrease in leptin (the hormone that leaves you feeling full). Even a 2 hour reduction of sleep / night for one week is associated with increased levels of pro-inflammatory cytokines and low grade inflammation, a condition known to predispose to insulin resistance and diabetes.
And if you are up late at night, eating when your body expects you to be asleep has a completely different affect on your body than eating during the day. Eating a meal at 1.30am will result in higher blood glucose levels, insulin and fats compared to the same meal eaten at 1.30pm therefore resulting in an increased risk of diabetes and heart disease in shift workers. Plasma glucose responses to exogenous glucose are markedly higher in the evening than in the morning and glucose tolerance is at it’s minimum during the night.
During a normal day, receptors in your brain fill with a chemical called adenosine that tells your body to go into rest mode. Caffeine is structurally similar to adenosine and fits into those same receptors. Your body becomes tired but you cannot feel it so you feel more alert for longer. Caffeine does a great job of keeping you awake and alert but your body continues to produce more adenosine which doesn’t get broken down by your body and can increase your stress hormones increase leading you to overwork as there are no cues to rest.
Caffeine starts to work in 25 minutes and has a half life of 5 to 8 hours depending on your physiology. This long half life means that consuming caffeine 6 hours before bed shows a measurable disruption to sleep. Drinking caffeine during the day will also disrupt any recovery naps that you take.
0.3mg of caffeine per kg of your body weight is enough to improve your performance and level of alertness – the equivalent of 1 cup of tea every 2 hours. But bear in mind that caffeine also decreases your sleep duration and causes suppresses slow wave sleep
Even changing your sleep duration by an hour or two can have a significant impact on your performance. Dropping from 9-7 hours sleep per night resulted in a loss of vigilance and lead to sluggishness in one study. Another showed that high level athletes sleeping for 10 hours a night improved their personal bests.
When learning a new skill it is best to practice it in s sessions 4 hours apart, sticking to the same skill each time and sleep 5 hours after practicing, and don’t get up to early either – performance increases when you experience more light sleep in the morning (6-8am). When asked to remember a list of words over a set time period, those that slept between learning and being tested remembered more than those who learnt and were tested later the same day even though both groups had the same time between learning and the test. And smelling something whilst learning and again whilst sleeping improves retention.
Naps can improve your performance in many ways:
- 5 min naps have no effect.
- 10 min naps had the most benefit in testing and showed immediate benefit after waking.
- 20 minute naps improve memory, alertness and reaction time and mood.
- 90 minute naps enhance creative thinking and your ability to grasp abstract concepts, they improve alertness and focus, improve muscle memory for new skills and abilities and promote the ability to learn facts and figures.
But be careful as longer naps can leave you feeling drowsy upon waking and may not show their benefits straight away. Naps show a greater benefit in performance than consuming caffeine and give less variable results, but a combined nap and caffeine were superior than either alone.
Mediation is an effective treatment for insomnia. In particular, morning mediation can help improve sleep at night. Not only that, meditation improves control of alpha rhythms which are thought to minimise distractions and therefore make you better at focussing and regulating how things that arise will impact you. Long term, it will even alter the physical structure of your brain, thickening regions associated with attention and sensory processing.
Solutions for better sleep health –
- Take part in at least 2.5 hours of moderate exercise a week.
- Lifting heavy weights builds muscles and aids sleep.
- Morning exercises results in you spending more time in reparative sleep.
- Turn screens down to minimum brightness and use an app such as Flux in the evenings. Hold the screen at least 12 inches from your face and wear orange tinted glasses to block the blue light.
- Sleep in a room with blackout blinds to reduce night time exposure to sleep disrupting light.
- Use red night lights.
- Your bedroom temp should be 18 degrees (65F) and 65% humidity.
- Baths decrease your body temperature when you get out and aid sleep. Cold extremities can help cause sleepiness.
- To avoid sleep inertia, keep naps to 25 mins or a full sleep cycle of 90 minutes. And plan time night time sleeping in terms of 90 minute sleep cycles.
- If you have problems getting to sleep:
- Apply a magnesium supplement to your skin or eat foods high in magnesium and aluminium – green leafy vegetables, pumpkin and sesame seeds, spirulina and Brazil nuts.
- Think pleasant thoughts.
- Create a sleep routine.
- Behave as if you are sleepy.
- Associate a piece of music with sleep.
- Use an essential oil such as lavender.
- If you have difficulty staying asleep:
- Play white noise to decrease noise disturbances that might wake you.
- Avoid alcohol.
- If you wake worrying about things, keep a notepad handy and write down the first steps to solving the problem so you don’t think about them as you try to sleep.
- If you wake hungry, make sure you consume 200 calories of carbohydrates before bed.