Since listening to a Stuff You Should Know podcast I thought I would try a switch in my caffeine habits. Like a true maverick testing science on myself. Not sure if you can really call someone a maverick for testing a reduction in caffeine on themselves but I have some sciency tools to do this test.

For sleep tracking I currently use a Garmin Fenix 3. The Garmin Fenix 3 is a sports watch and activity tracker that does everything you need and more. From dedicated triathlon training, to running, step counting and of course for this test sleep tracking. A recent update from Garmin means you do not need to tell the watch when you go to sleep. It knows! 

What's required for this little test?

Garmin Fenix 3

Garmin Fenix 3

Less Coffee

And a lot less coffee (if you are interested in training with caffeine read our post here)

Caffeine before sleep

When you are cutting back from a regular supply of strong tea throughout the day it takes a regular coffee or tea drinker to know just how hard this sort of thing is. Well I thought it would be hard but it has been remarkably easy for me. So why the test? On the podcast they reminded me that caffeine has a half life of 6 hours. This means after 6 hours you still have 50% of the effect in your system. We all know about the stimulating effects and addictive effects of caffeine so if you have a cup of tea or coffee at 3pm, and one at 5pm then this is more or less the same as having a full coffee at around 10pm. Or maybe even a can of energy drink. Right at bedtime. What they said was you may fall asleep with no problems, but your deep sleep will be effected. 

From Garmin you get a breakdown of deep and light sleep. Plus awake time, so in theory seeing if a 2 week test will make any difference will be fairly easy to measure. 

Caffeine Affects Sleep

From my reading on the NHS and various other reputable sites, caffeine will affect your sleep, but not everyone. Everyone's body treats caffeine differently. And my results from the Garmin the two weeks up to the test were as follows:

Date Deep Sleep Light Sleep % of Deep Sleep
1/5/2016 2:40:00 5:08:00 34.19%
1/6/2016 3:03:00 4:17:00 41.59%
1/7/2016 2:33:00 4:43:00 35.09%
1/8/2016 3:28:00 4:16:00 44.83%
1/9/2016 3:19:00 3:32:00 48.42%
1/10/2016 4:22:00 6:12:00 41.32%
1/11/2016 2:33:00 5:21:00 32.28%
1/12/2016 2:44:00 5:32:00 33.06%
1/13/2016 2:39:00 5:36:00 32.12%
1/14/2016 2:26:00 5:20:00 31.33%
1/15/2016 2:05:00 5:57:00 25.93%
1/16/2016 3:34:00 5:14:00 40.53%
1/17/2016 2:38:00 5:26:00 32.64%
1/18/2016 2:59:00 4:31:00 39.78%
1/19/2016 2:37:00 4:39:00 36.01%
      36.61%

The test kicked off with the following rules. Going from 10+ cups of tea and coffee per day up until about 5pm to just one in the morning first thing. No other caffeine. Without other people to compare my stats to I am just looking for a blame why my deep sleep is just a little over half (but very broken up through the night). 

So bring on two weeks of sleep tracking with just once cup in the morning.

Date Deep Sleep Light Sleep % of Deep Sleep
1/20/2016 2:30:00 4:51:00 34.01%
1/21/2016 3:35:00 4:42:00 43.26%
1/22/2016 2:41:00 5:46:00 31.76%
1/23/2016 3:02:00 4:45:00 38.97%
1/24/2016 2:31:00 5:10:00 32.75%
1/25/2016 2:10:00 3:39:00 37.25%
1/26/2016 2:47:00 5:14:00 34.72%
1/27/2016 2:26:00 4:50:00 33.49%
1/28/2016 4:12:00 3:47:00 52.61%
1/29/2016 2:10:00 5:01:00 30.16%
1/30/2016 3:14:00 3:50:00 45.75%
1/31/2016 2:51:00 6:19:00 31.09%
2/1/2016 2:05:00 5:28:00 27.59%
2/2/2016 2:11:00 4:01:00 35.22%
      36.33%

Conclusion.... No change at all! Well at least for me there is no change. 36% of my sleep is deep sleep (according to my trusted Garmin Fenix 3)

I had caffeine and can't Sleep

Most of us have all been there. Worked out late at night and hand some energy caffeine laced drink. Or been out and about. Once you are home, lying in bed, thinking "why can I not sleep?". I do think caffeine gets more of the blame than is fair. Maybe it is just your internal 'mind disco' still playing tunes and reviewing the last few hours rather than the caffeine. 

Sleep Data from the Garmin Fenix 3

From the Garmin Fenix 3 via your phone or their Garmin Connect online account you let the watch know your typical sleep times (most of us have some sort of routine) and the watch will record your sleep.

Sleep Movement Garmin Fenix 3

The graph above is the movement during sleep. Garmin will interpret this data into deep and light sleep and that looks like the following.

Garmin Fenix 3 Light and Deep Sleep Comparison

Typically activity trackers that monitor your sleep will flag up just how little sleep you have. Read up on sleep and how much you should get. Then you will realise it is important and the deep sleep is what counts. In the chart above deep sleep is represented by the dark navy bars and the light sleep the light blue. Pink is awake time.

For most people an activity tracker will tell you to walk more. Move more. Sleep more. But typically they will make you healthier if you listen to them. Once you have purchased a fitness device read our top tips on how to get the most out of your tracker

What else does the Garmin Fenix 3 do?

The Garmin Fenix 3 is the athletes choice when it comes to training. Coming soon, built in heart rate tracking. It monitors you steps. Records via GPS your runs. Tells you your cadence and stride length. Will record your pool swims and sea swims. Works as a watch. Lets you download new watch faces from the app store. The list goes on. 

Read up our review on step counting with the Garmin Fenix 3

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