The importance of light

Many of us spend a large portion of our time inside. Our light exposure during the day is, therefore, generally less than it would be if we were outside. Your circadian rhythm is a 24-hour body clock that regulates the timing and duration of sleep and wakefulness. This ancient system is intrinsically linked to the external day/night cycle by a group of brain cells that respond to light and dark inputs received via the optic nerve (National Sleep Foundation, 2018). The 24-hour body clock needs bright light exposure during wakefulness and dimmer light to prepare for sleep. Spending time outside during the day is a good way to regulate the circadian rhythm. Aim for a minimum of 30-60 minutes natural light exposure on a daily basis. If this is not possible, bright, artificial light can help too.

 

Bright light exposure before bed will suppress melatonin, the hormone that regulates your circadian rhythm and hence when you feel sleepy. Dimming the lights a few hours before bed may therefore help with the onset of sleep.

 

Screens, tablets and phones

The impact of bright light on your circadian rhythm and on melatonin is one of the reasons why it is advisable to avoid screen use before bed. Even with a blue light filter, your Suprachiasmatic Nucleus, the master body clock in your brain, will still be receiving light input from the eyes. In addition, the things you do on screens – working, sending emails, social media, games - tend to be cognitively stimulating and not conducive to sleep. Watching TV before bed is fine (as we tend to sit further from the light source), but be aware of what you are watching and the effect it has on you. Anything that sets off the flight or fight response is not going to put you in a good position for sleep.

 

Lifestyle factors

Studies show that regular exercise can help improve the quality of your sleep (Loprinzi and Cardinal, 2011). Aim for at least 30 minutes on a daily basis. However, do not take exercise late in the evening, as this can stimulate the nervous system, delaying sleep onset.

 

Caffeine suppresses adenosine, one of the factors thought to be involved in the homeostatic process (Bjorness and Greene, 2009), the other system that works with our body clock to regulate our sleep cycles. Studies show that sleep may be affected up to six to eight hours before intended bedtime (Drake et al., 2013), so use this as a rough guide.
Equally nicotine is a stimulant, and stimulating your nervous system before bed is not helpful as it will be harder to fall asleep and to stay asleep (Jaehne et al., 2009).

 

Alcohol is sometimes used as a nightcap before bed. While it can help with getting to sleep initially, there is then a tendency towards fragmented sleep through the night or early morning waking (National Sleep Foundation, 2018). In addition, alcohol changes the structure of your sleep by suppressing REM (rapid eye movement) sleep, leaving you feeling unrefreshed. If you do have a drink, it's best to leave a couple of  hours before going to bed so the alcohol is already wearing off and to have a few alcohol-free nights a week to avoid becoming dependant on alcohol to sleep.

 

Don't go to bed hungry but don’t eat a big meal just before bedtime (National Sleep Foundation, 2018). Hunger can cause wakefulness so a light snack before bed can be helpful if you have eaten your last meal early in the evening. Conversely, going to bed on a full stomach can keep you awake. Snacking in the night should be avoided as your body may come to expect food at this time.

 

Bedroom environment

Keep your bedroom for sleeping. Don't watch television, make phone calls, work, eat or drink while you're in bed (sexual activity is the exception). This is because you want to associate your bedroom with sleeping not wakefulness (The Sleep Council, 2018).

 

Make sure you are comfortable in bed with adequate bedding for the season so you are the right temperature. Aim for a cool environment of 16-20 degrees as being too hot or too cold can disturb sleep. In additional, sleeping in a dark room is a good idea so use thick curtains or blinds (The Sleep Council, 2018).

 

Sleep routines

Aim for consistent bedtimes and rise times across the whole week. This will help to regulate the processes that control your sleep (Sleepio, 2018). If you need to lie in at the weekend, it is probably because you are not getting enough sleep on week days so aim to change the latter. Different bedtimes and rise times at the weekend compared to the week can create problems getting to sleep on Sunday night and waking up on Monday morning which can then affect your performance at work.

 

Create a regular and consistent wind-down routine, an hour before bedtime (Sleepio, 2018).  These activities will come to be associated with sleep times and the wind-down allows you to switch off from the day to get ready for sleep. Stop any work or tasks and do something relaxing such as having a warm bath, reading, watching TV, listening to music or relaxation exercises. These should be done in a relaxed environment but not in the bedroom.

 

Sleep well, live well.

 

References

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