Family doctor

Overview

Although we spend over a third of our lives sleeping, surprisingly little is known about the function of sleep. Current theories suggest that sleep plays a critical role in memory consolidation, learning, damage repair and energy conservation.

Although individuals have varying sleep requirements, the value of getting a good night's sleep is universal and just as important as good nutrition and physical activity.

Sleep hygiene is a term used to describe a set of environmental and behavioural recommendations to improve the quality of sleep. It was initially developed for the treatment of insomnia, but has also proven to benefit those who do not suffer from sleep problems.

The anatomy of sleep:

There are two main types of sleep: non-rapid eye movement (NREM) sleep and REM sleep.

In healthy sleep, NREM has four stages. These stages get deeper as they progress and last around 90 minutes in total.

REM sleep on the other hand only lasts around 10 minutes and is the period of sleep in which dreams typically occur and the brain is most active.

This 100 minute cycle (90 minute NREM and 10 minute REM) gets repeated four to six times in one night. As sleep progresses, the amount of time spent in deep sleep (stages 3-4 NREM) decreases and the time spent in REM sleep increases. In the last cycle of sleep, most people spend as much as an hour in REM sleep.

Waking up during a cycle of deep sleep is a particularly unpleasant time to be woken up and this is part of the reason that it is important to maintain regular sleeping and waking times.

Sleep regulation

As well as cycling through different stages within sleep, our bodies cycle through a 24 hour sleep and wake cycle, often referred to as circadian rhythm. This rhythm is controlled by a centre in the brain called the suprachiasmatic nucleus (SCN). Many different factors influence the functioning of this part of the brain including light, social activities and stress. Even short bouts of high intensity light can alter the body’s natural clock, for example computer use in a dark room right before bed.

Circadian rhythms play an important role in controlling the timing of hormone release including cortisol, melatonin, thyroid stimulating hormone and insulin. They also influence the timing of peak liver metabolism and kidney function.

So what exactly are the principles of sleep hygiene?

Sleep hygiene theory focuses not only on the physical aspect of sleep but also on the mental, pre-sleep environment, both are equally important.

The main recommendations include:

• Sleep only as much as you need to feel rested and then get out of bed once you do
• Keep a regular sleeping schedule
• Avoid caffeine, nicotine and alcohol in the afternoon and evening before bed
• Exercise regularly for at least 20 minutes 4-8 hours prior to sleep
• Do not go to bed hungry or having drunk excessive amounts of water
• Ensure your bedroom environment (temperature, noise, light) is sleep promoting, this includes minimal noise, light and a comfortable temperature
• Limit the use of computer, TV, and other screens which light up directly before bed
• Manage stresses and worries before you try and sleep
• Some sleep clinicians suggest strictly limiting the bed to sleep and sex, whereas others allow listening to music and reading in bed

Let’s explore some of these recommendations in a little more detail:

Regularity of cycles

In terms of sleep improvement, getting out of bed at the same time each morning is more important than going to bed at the same time each night. The main drive for sleep should be sleepiness (yawning, eyelids drooping, nodding off), which may vary depending on what has happened during the day. Waking up at a regular time each morning is beneficial as it regulates sleep cycles and circadian rhythms. Increased lifestyle regularity has also been shown to improve sleep.

Caffeine

Caffeine blocks a sleep-promoting chemical called adenosine in the brain. Levels of caffeine peak 30 minutes after intake and last between 3-7 hours (this increases with age). It is well known that consumingcaffeine close to bedtime disrupts sleep in a dose-response relationship (the more caffeine you consume, the more sleep disruption you will experience). It is important to remember that coffee is not the only source of caffeine; other sources include tea, dark chocolate and energy drinks.

Current sleep hygiene guidelines vary in advice regarding caffeine intake, some recommend complete abstinence while others recommend avoiding caffeine in the afternoon and evening. People vary greatly in their genetic predisposition to caffeine tolerance so cutting caffeine out may be more helpful for some than others.

Nicotine

Nicotine use before bed also disrupts sleep as it temporarily increases the body’s state of arousal. In particular, nicotine use is associated with later sleep onset and more frequent early morning awakenings.

Unlike caffeine, you cannot develop a tolerance for the adverse effects of nicotine. This means that even long-term smokers are just as susceptible to the disruptive effects of nicotine as people who have just started smoking.

Alcohol

Alcohol is associated with a faster onset of sleep and an increased period of deep sleep during the first part of the night, however as alcohol is metabolised, sleep becomes lighter and the REM component of sleep increases disproportionately. Because deep sleep is particularly important for repair and memory consolidation, alcohol reduces your sleep efficiency and makes you more susceptible to being woken up.

Exercise

Regular exercise is a common recommendation to improve sleep. The benefits of exercise on sleep are mediated through changes in body temperature, decreased arousal and increased adenosine levels. Even 20+ minutes of exercise has been shown to bring sleep on quicker and increase total sleep time. This is proportional to the amount of exercise you do rather than the mode of exercise and your level of fitness.

The most robust evidence for sleep benefit from exercise comes when you exercise 4-8 hours prior to sleep.

Stress

Psychosocial stress is shown to increase pre-sleep arousal and impair sleep. Relaxation techniques have been proven to be beneficial in decreasing stress before bed. Particularly effective, is the practice of mindfulness. This involves shifting focus to the present moment without judgement and in doing so, creating a state of mind that is incompatible with the distraction of everyday life stresses.

Noise

The conscious appreciation of noise has a clear impact on sleep disturbance, but so too does background noise we don’t consciously hear during sleep. Noise during sleep increases our number of arousals (conscious and unconscious) and results in lighter, less effective sleep. Other aspects of the physical environment such as light and temperature are shown to impact on sleep. Most of the sleeping recommendations regarding the physical environment are based on common sense such as reducing light, noise and maintaining a comfortable temperature in the bedroom.

Other tips:

• Get rid of the bedroom clock
• Try and keep the room as dark as possible and remove any lights or electronic devices that emit light
• Don’t put pressure on yourself to sleep for the golden ‘8 hours’ this may not suit you, everyone is different
• Decrease time spent in bed, only go if you are very sleepy
• Try and eliminate napping
• Take a bath or engage in a relaxing activity before bed
• Make a worry list to get things out of your head before laying down to sleep, particularly if you are someone whose mind races before bed
• Avoid working intensely before bed, make an effort to unwind before
• Eat a light snack before sleep (unless you suffer from reflux)
• Limit liquids before bed to avoid needing to get up in the night to pee
• Avoid trying hard to sleep, sleep should be passively allowed, if you do find yourself lying in bed awake for over 20 minutes, get up and read in the lounge or do a non-stimulating activity till you feel more tired
• Don’t confuse fatigue with being tired
• Keep a sleep diary to observe your current patterns, recording details such as caffeine intake and exercise levels throughout day, then try and modify behaviours to see if you can encourage more regular, deeper sleep
• Try and partake in a meditation/mindfulness exercise before bed or join a mindfulness group and practice regularly during the week to minimise overall stress levels
• Make an effort to make your bed before you get into it, removing any clothes or unwanted objects on the bed and in the room

Other methods of behavioural management for improving sleep quality: (talk to your doctor or sleep specialist about administering these)

Stimulus control:

People with insomnia tend to associate their bed and bedroom with the frustration they feel from an inability to sleep. To minimise this association, it is important that people spend as little time as possible in their beds when they aren’t sleeping. Stimulus control therapy aims to reduce this association. It recommends that people do not go to bed until they are incredibly sleepy. They should not spend more than 20 minutes awake in bed. After 20 minutes of being awake, they should leave their room and participate in a relaxing activity in another room of the house.

This activity shouldn’t be enjoyable such as watching TV or eating, as this only reinforces waking behaviour. Instead it should be relaxing like engaging in a meditation, reading or listening to relaxing music. This process of getting up after 20 minutes should be repeated if need be.

An alarm should be set for the same time each morning including weekends, regardless of how many hours of sleep was achieved that night. Daytime naps are not allowed. The benefits from this therapy may not be initially sensed but will develop over time.

Sleep restriction therapy:

Sleep restriction therapy (as the name suggests) restricts the amount of time spent in bed. Many people with insomnia try and counteract the sleep they have lost by staying in bed longer than they should. This shifts their circadian rhythm and decreases their drive for sleep the following night. Sleep restriction therapy involves keeping a sleep log of the number of hours spent in bed relative to the hours of sleep had.

The sleep clinician works out the patient’s sleep efficiency based on these hours and prescribes a restricted amount of time spent in bed until the patient reports better sleep with no residual daytime sleepiness. Naps are not allowed in this form of therapy either.

Links:

Meditation guides:

http://www.calm.auckland.ac.nz/

More information on sleep

http://www.sleepeducation.com/

http://yoursleep.aasmnet.org/pdf/sleepdiary.pdf

References:

Black DS, O’Reilly GA, Olmstead R, et al. Mindfulness meditation and improvement in sleep quality and daytime impairment among older adults with sleep disturbances: a randomized clinical trial. JAMA Intern Med. Published online 16 Feb 2015.

Bootzin RR, Perlis ML. Nonpharmacologic treatments of insomnia. J Clin Psychiatry 1992; 53:37

Gerrig, R. J., & Zimbardo, P. G. (2002). Psychology and life. Boston: Allyn and Bacon.

Irish LA, et al., The role of sleep hygiene in promoting public health: A review of empirical evidence, Sleep Medicine Reviews (2014)

Schulz P, Steimer T. Neurobiology of circadian systems. CNS Drugs.2009;23 Suppl 2:3-13.