How much power do you need to wake up a man?

[TobiWan]

Hey,
Let us assume that before we go to sleep, we put on something like a wristwatch. We set the right time and it wake us up with the help of electrical impulses. How many watts can safely wake us up?

[brabus]

If an electrical discharge woke me up, my mood would be pretty freakin' bad.

Are you really planning to do that? It all depends on where you put the electrodes and the waveform you are generating.

[TobiWan]

The electrodes would be on the watch that we would have on our hand. I hope the watch would look small. Something that we can easily take off and put on.

If an electrical discharge woke me up, my mood would be pretty freakin' bad.

I don't want it to be hurtful, quite opposite, I would like it to wake us up in the most gentle way.

[Kalvin]

Ramp up the pulse amplitude gradually, then the person may wake up gently instead of being shocked suddenly by the watch.

[TheWelly888]

There is at least one model of wristwatch already available that vibrates when it's alarm goes off.

[Kjelt]

I guess it depends on the person, there are persons that have a high tolerance of pain they just don't feel it.
So you need to make it adjustable anyway and you can test it on yourself, let us know the results of the experiment.

[NivagSwerdna]

Hey,
Let us assume that before we go to sleep, we put on something like a wristwatch. We set the right time and it wake us up with the help of electrical impulses. How many watts can safely wake us up?

1. Just say No
2. Such a device does exist https://www.amazon.com/Pavlok-Shock-Clock-Wake-Trainer/dp/B01EZ77IOY
3. Just say No

[rstofer]

I suspect the buzzer in one of the Garmin fitness devices, like the Forerunner 230, would work.  The instructions talk about setting the alarm and various sounds but I don't know if the vibrator is one of the options.

The vibrator is used to tell me to 'Move' from time to time.

Apparently it is possible to set up the alarm clock to use the vibrator on the 230 model:
https://forums.garmin.com/forum/into-sports/running/forerunner-235-aa/116719-wake-up-alarm

I seriously doubt that the alarm has a 'snooze' feature.

[MarkF]

You just need a little mechanical T-handle like Our Man Flint.

[mzzj]

Couple of pulses equivalent to TENS stimulator ie 100 volts, 50mA and 100uS is probably going to wake you up pretty sure. 100v*50mA*100uS= 0,5 mJ of energy per pulse, lets say it takes 5 pulses to wake you up... so that would be 2,5 mJ 
Small MLCC cap to store the charge, loaded with simple boost converter or charge pump.

[janoc]

The fastest and most reliable way how to get a person out of the bed in the morning has to be probably this:


Or if you prefer a bit less drastic solution, then one of these:

[atmfjstc]

Setting aside the huge potential for injury, I happen to know of some heavy sleepers for whom even the bed ejection method might not be enough At this point one is better off devising some sort of system to nag you into going to bed early instead.

All this makes me think of that modern proverb according to which a huge chunk of lifestyle technology seems to be dedicated to substituting the functions of one's mom.

[james_s]

I can think of few methods of waking up in the morning that sound less pleasant than an electric shock. I *hate* getting shocked.

[Doctorandus_P]

A few kW directly into the testicles should do the job.

Bit more serious:
You do not want andy DC current through your body because it will have electrolysis effects, which create acids which damage cells. So use an H-bridge ( discrete or stepper motor driver, whatever) or an transformer to generate an AC voltage / current (Throw in a DC blocking cap, just to be sure).

A "human body model" is often stated as a 1k to 1.5kOhm resistor in series with a few uF (leaky) capacitor. Currents upto 20mA should be pretty safe, but already painfull, currents below 2 to 5 mA usually can't be felt at all.
You also want some voltage to get some current going.
In TENS devices and such a voltage of 60V to 100V is common, and pulses with alternate polarity are used to keep the DC bias at 0V. Pulse widths should be in the low micro second range.

With the parameters above you can start experimenting. Start with a dummy load, then experiment on yourself, probably with a lower initial voltage untill you get a feeling that matches your wishes. For a better "feel" a series resistance of a few kOhm is also often used on the output.

An easy way to start experimenting is with the black box (with schematic) reverse engineerd by BigClive.

[bson]

A swift kick from my wife is usually all it takes.

[Bud]

To me it takes zero external energy. If i need to wake up at a particular time, i just think to myself 2-3 times that i will wake up by that time. It may also help to visualize the clock with clock hands positioned at the needed time.  I usually wake up 2-3 min before the target time, without a need for an alarm clock, no matter how tired i was before going to bed. It is all inside us. Try it next time.

[janoc]

To me it takes zero external energy. If i need to wake up at a particular time, i just think to myself 2-3 times that i will wake up by that time. It may also help to visualize the clock with clock hands positioned at the needed time.  I usually wake up 2-3 min before the target time, without a need for an alarm clock, no matter how tired i was before going to bed. It is all inside us. Try it next time.

I would probably spend the entire night awake being stressed out that I could oversleep if tried this. Great that it works for you but I would say you are far from the majority here ... 

[metrologist]

To me it takes zero external energy. If i need to wake up at a particular time, i just think to myself 2-3 times that i will wake up by that time. It may also help to visualize the clock with clock hands positioned at the needed time.  I usually wake up 2-3 min before the target time, without a need for an alarm clock, no matter how tired i was before going to bed. It is all inside us. Try it next time.

Now you've exposed how old you are. That skill does not materialize until middle age. I've been trying it for a few years and am getting better at it. It is so empowering being in control.

[iMo]

The biggest problem here could be the skin resistivity depends on many factors. It could be ohms or megaohms.. It will work best with the persons experiencing night sweats

[Rerouter]

Metrologist. You can have that skill as a young person aswell. Ive had it since I was 16,

Most mornings I wake up. Grab the phone to see the time and 5 seconds later the alarm starts. No matter if its 6am or 1:30am

The only annoying thing about this skill is you generally will wake up early most weekends. It doesnt really ever switch off.

[metrologist]

Well, mine actually works because I check the clock every 5 minutes. If it really worked, there would be no weekend problems. 

[Jester]

To me it takes zero external energy. If i need to wake up at a particular time, i just think to myself 2-3 times that i will wake up by that time. It may also help to visualize the clock with clock hands positioned at the needed time.  I usually wake up 2-3 min before the target time, without a need for an alarm clock, no matter how tired i was before going to bed. It is all inside us. Try it next time.

Same thing for me, I very very rarely use an alarm, only when I have a early flight or something like that.

[Mechatrommer]

I'm thinking 'spot to the face' water sprinkler system, a lot less hazard than a shock or tipping bed, and lesser pressure than having to meditate wake up time before sleep. I was learning as lucid dreamer and to some extend succefull, i believe its a good way at controlling sleep duration, but nothing beats zero pressure sleep, so i abandon the technique because it takes some mental strength to maintain control. not having to think anything and sleep peacefully until my body says enough is a bless but wake up late is a curse, as i think i've screwed my biological clock by occasonally skip night sleep doing hobby. The only thing that regulate my clock now is the family, wife and my daily job. If its holiday, the bio clock pll can be detuned to not 24 hours to 36 hours frequency... meaning at one day i can sleep during the day sun hot up perpendicular on the sky, and the next cycle i will be sleeping earlier than normal people during the night.