Sleep is a vital part of physical and mental health, but many of us know very little about this aspect of life. In the same way that our bodies get hungry when we don’t eat, our bodies feel sleepy when we don’t sleep. And just like eating regularly to fix feelings of hunger, sleeping regularly can help relieve sleepiness. Although the exact science behind it is unknown, scientists have a few theories.
One proposition is the inactivity theory.
It is an evolutionary idea that animals who were able to stay still for longer periods were less of a threat to predators, and thus survived longer. Ultimately, it is an adapted behavioral strategy.
A second is energy conservation theory.
Animals who reduced energy expenditure at certain times of the day when searching for food was least efficient had higher chances of survival. It is another evolutionary adaptation to aid survival.
The third is restorative theory.
Sleep has a restorative nature on the human body. Studies in which animals were sleep deprived resulted in weakened immune systems and, in some cases, death. The prefrontal cortex is a part of the brain that is responsible for higher functioning and reasoning. It is particularly vulnerable to lack of sleep. When awake, neurons in the brain build up a byproduct called adenosine. A buildup of adenosine may contribute to feelings of sleepiness. When we sleep, our body has a chance to clear this from our system. Safe to say, sleep has restorative effects on the body.
Finally, there is the brain plasticity theory.
Sleep plays an integral role in the brain development of infants and young children. A significant portion of their 13 to14 hours of sleep each day is REM sleep, which is the stage of sleep when dreams most occur. This theory is not entirely understood, though there are profound effects on the brain from lack of sleep in relation to a person’s ability to develop, learn and perform.
The Sleep Health Foundation Australia estimates that insufficient sleep affects 39.8% of Australian adults. The cost of insufficient sleep may be greater than we think. Studies suggest sleeping five hours or less per night increases the risk of mortality by up to 15%. Inadequate sleep leading to drowsiness contributes to one death per day on the roads.
Lack of sleep can contribute to heart disease. A recent study showed elevated blood pressures in people with hypertension after a single night of poor sleep. One study reviewing the correlation between sleep and cardiovascular disease in women found that both too little sleep (less than six hours) and too much (over nine hours) increase the risk of heart disease.
Insufficient sleep can contribute to obesity. During sleep, our bodies secrete hormones which help control appetite, energy metabolism and glucose processing. Insufficient sleep is associated with lower levels of the hormone that tells our brain it’s had enough food (leptin) and higher levels of the hormone that stimulates appetite (ghrelin). We might be more prone to snacking on unhealthy, high-energy foods or relying on caffeine for quick bursts of energy. Insufficient sleep has also been associated with increased insulin levels after meals. Higher insulin levels can cause weight gain, a risk factor for diabetes.
As mentioned earlier, sleep deprivation has been found to affect immune function. When we are sick, our natural reaction is to sleep. An adaptive evolutionary theory suggests that those who faced infection and slept outlived those who did not. This suggests that sleep has immune protective qualities.
Prolonged insufficient sleep can raise the risks of developing a mental illness. Insufficient sleep makes us vulnerable to life stressors and can result in mood instability. It makes us irritable and more likely to experience negative emotions such as anger, frustration, irritability and sadness.
Just as we can make healthy lifestyle choices with diet and exercise, we can make healthy choices with sleep. Adults require eight hours of sleep each night, and teenagers need nine to 10 hours. These requirements change depending on age, physical activity levels and general health. The Sleep Health Foundation believes that up to 20% of insufficient sleep is due to behaviors that restrict sleep.
Here are some tips and tricks to get better sleep:
- Establish a relaxing nighttime routine. Plan for relaxing activities an hour before bed. This might look like a relaxing bath or shower, reading or a mindfulness exercise (You can search for mindfulness applications on your smartphone; many will have a sleep-specific exercise). Avoid stressful and stimulating activities like work or emotional conversations. If stressed, the body will stimulate the hormone cortisol, which is known as the stress hormone and is associated with alertness. If you ruminate on stressors before bed, try writing them down.
- Have a sleep-ready environment. Use something for white noise, whether it’s a running fan or a white noise machine. Keep the room at a comfortably cool temperature between 15 to 23 degrees Celsius. If a pet regularly wakes you, it may be time to consider a new sleeping location for them. Avoid having TVs, computers and work material in the bedroom. Keeping these away will help develop stronger associations for healthy sleep routines. Keep bedrooms for sleep and sex only.
- Go to sleep when you’re truly tired. If you have trouble falling asleep, it can lead to frustration and negative emotions. If you don’t fall asleep within 20 minutes, try getting up, doing something relaxing (such as reading under dim light or listening to music) and returning to bed when you are feeling tired.
- Avoid technology in the bedroom (Including phones). Electronic devices emit a blue wavelength, interrupting the secretion of the hormone melatonin, which plays a vital role in circadian rhythms. In fact, blue light interferes with this cycle twice as much as regular light. Be sure that lighting in the bedroom is dim. Avoid using technology two to three hours before bed.
- Use morning light to reset your sleep/wake cycle. Exposing yourself to natural morning light helps keep your body on a healthy sleep/wake cycle. So can smelling activating scents like mandarin, peppermint or lemon.
- Be consistent. Go to bed at the same time and wake up at the same time. Developing regular patterns helps your body set an internal clock.
- To nap or not to nap? Avoid if you can, but if you must, keep naps brief and no later than 4pm.
- Avoid chemicals. Caffeine, alcohol, nicotine, energy drinks andfizzy drinks are all considered chemicals that interfere with sleep cycles. Avoid these items four to six hours before planning to sleep.
- Diet. Having a large dinner right before bed may cause indigestion and keep you up. Plan to have your dinner meal earlier and give your body time to digest it. If you suffer from nighttime hunger, plan on snacking on small portions of food that won’t disturb sleep, such as or carbohydrates. Avoid high sugar snacks.
- Water. Having your recommended two to three litres of water throughout the day is important, but too much water late at night may be causing you to wake to use the bathroom. Avoid drinking too much water before bed.
- Exercise. We know exercise is important in keeping physically healthy and managing stress. Exercise is a natural way to reduce cortisol, the hormone produced when the body is in a state of stress. Make sure you’ve finished exercising three hours before bed as exercise has activating effects on the brain.
- Evaluate. Track any progress by recording sleep strategies in a calendar or diary. Note the bedtime and wake time, hours of sleep achieved each night, any reasons for waking (e.g. toilet, nightmare, anxieties) and energy levels the following day. The information collected may be valuable to show your GP if insufficient sleep persists.