How sound-based alarm clocks affect sleep

If you’ve ever felt groggy, weak, unable to concentrate and generally off after waking up, it might just be time to consider how you wake up. Most people will use a sound-based alarm to shock themselves out of sleep; a solution employed for hundreds, if not thousands of years to bring themselves into wakefulness.

In isolated cases this has led to reactions like seizures and irregular heartbeat, but for most of us the reaction is not that extreme. In any case, whether you’re an early bird, night owl, shift worker or anything else in between and want to be at your best throughout the day, it’s best to train yourself not to use any sort of alarm at all (a hard task, and very likely to result in you waking up later than you’d like) or to use a light-based alarm clock.

Let’s take a look at the science behind why these are better ways to wake up.

Not all sleep is the same

Sleep has a number of stages to it, each with their own distinct function and features, e.g. amount of body and eye movement, breathing rate as well as the ease from which you can wake from them. Stage 1 sleep is the easiest to wake from and stage 3 is the most difficult. Naturally, a good alarm clock will wake you up regardless of what stage of sleep you might be in so that you can go about your day, and loud noises are a sufficiently alarming(!) way to arouse a person from any stage of sleep, hence the success of the modern, sound-based alarm clock. There’s one main problem with not taking account of the stage of sleep you’re in prior to waking and instead waking at a regular time; this is due to something called sleep inertia.

The basics of sleep inertia

Sleep inertia is a state of reduced mental and physical performance that occurs after waking and is characterised by poor decision making, bad mood, feelings of disorientation and confusion as well as muscle weakness. Typically, these effects only last a few minutes into waking but have been reported to persist for as long as four hours. In some cases, these symptoms can be so severe that the similar, negative effects of not sleeping at all the night before may not feel as bad.

There are multiple factors influencing the severity of sleep inertia, but the most critical is the stage of sleep that you wake from; the deeper the stage of sleep that has been interrupted, the worse the resulting sleep inertia will be. For example, if you were to wake from stage 3 (deep sleep), you would have more severe sleep inertia than someone woken from stage 1, (shallow sleep).

Given that we don’t know what stage of sleep we’ll be in when a sound-based alarm clock goes off and that the severity of sleep inertia on waking depends on the stage of sleep we wake up from, we don’t know just how bad an episode of sleep inertia will be from day to day.

Since many people are sleep deprived due to the misalignment of their sleep cycle and their daily schedule (e.g. going to bed late and having to wake up early, working shifts or being in a job that requires long periods of being awake), it is likely that they spend more of their sleeping time in a deeper stage of sleep, meaning that when their alarm does sound and they wake up, their symptoms of sleep inertia will be severe, leading to an awful start to the day on top of a worsening of their already existing sleep deprivation. So it’s only reasonable to ask “surely there must be a better way to wake up?” Indeed there is, a light-based alarm clock, or dawn simulating light.

The light-based alarm clock

The Human body is remarkably sensitive to light and dark and cues the release of hormones associated with wakefulness (in bright environments) and sleepiness (in dark environments) as part of what’s called a circadian rhythm. Because of this, a light based alarm clock is a more natural alternative to a sound-based alarm clock.

Light based alarm clocks typically work by raising the intensity of the light they emit shortly before your desired waking time, so as to mimic the effect of a rising sun. This is important for a few reasons. The more gradual “waking up” process is less shocking and liable to reduce the effects of sleep inertia in part because the light is less likely to wake you during deep sleep, meaning you feel fresher at the start of the day. In addition, studies on the effect of light exposure prior to waking up suggest your mood on waking will be improved when using a light-based alarm clock to wake up, as well as experiencing cognitive benefits such as improved memory and concentration. On top of that, the more natural, gradual waking process may reduce the likelihood of a “post-lunch dip,” where you feel sleepy in the afternoon.

The benefits don’t stop there; because light exposure regulates the cycle of hormones associated with feeling sleepy and awake, sleep deprived populations like those mentioned above, might benefit from the use of a light-based alarm clock as part of a program to establish a more regular sleep pattern leading to an overall reduction in sleep deprivation.

Why not a mobile phone?

Advances in mobile technology have been rapid over recent years with smartphones replacing dedicated sat nav devices, mp3 players, cameras and yes, the alarm clock. Although many sophisticated apps which take into account your sleep phase and can wake you with either sound or light, there are two main problems with them. The first is that a mobile phone display simply isn’t bright enough to simulate a rising sun, and generate the necessary hormonal response. The second is that it requires the mobile phone to be close to you while you’re in bed. With that comes the temptation to use it before going to sleep, which leads to poorer quality sleep due, in part, to the large amount of blue light that mobile phone displays emit, which has a stimulating effect.

Given the importance of good quality sleep to overall health, it’s well worth considering replacing your sound-based alarm clock and getting a light-based solution so you can start reaping the benefits.

Summary of key points

  • Sound-based alarm clocks shock you into waking up, leading to sleep inertia.
  • This results in you feeling groggy, strange and not at your best.
  • Waking up using light instead can make your feel more alert, can enhance your mood and lead to better memory and concentration throughout the day.

What’s next?

If you don’t already own a light-based alarm clock, we recommend you get one. The downside is that they can be expensive. Prices start around £25, with top-end solutions costing up to £140. However, we feel that it’s an investment worth making as a light-based alarm clock will likely improve your mood and productivity for years to come. So, for most people, they are a sound investment.

You can find a huge variety of light-based alarm clocks on Amazon.

All the ones we have experience with are straightforward to set up. You should also think about investing in thick curtains or blackout blinds to control your light exposure completely.

Maximise control with blackout blinds

Controlling light to help you wake ‘naturally’ can make a large difference to how fresh you feel when you wake up and increase the chances that you can get into a routine and improve your sleep. Unfortunately it won’t fix everyone’s sleep problem. Depending on the severity of your sleep issues you might need more help. Sleepstation offers online CBTi therapy which has been clinically proven to be the most effective method of treating all forms of insomnia. You can find out if Sleepstation could help you sleep better by completing a short questionnaire.

Did you know?

Sleep deprivation costs the UK economy around £40B per year.