Bunk LedgerCPAP in a sleeper cab (2026)
Not medical advice. Talk to your doctor.
A CPAP in a sleeper is a power problem and a water problem before it is a shopping problem. The machine on your prescription is the machine. This note does not rank models, and it does not tell you to start, stop, or change a pressure.
The photo is a machine in a clinic-style setting. It is not a recommendation.
What the label is for
The Sleeper Cab Power Planner starts a CPAP at 60 watts with the heated humidifier off and 90 watts with it on. Those two numbers are planning defaults so the form is not empty. They are not a measurement from a truck, and they are not the spec of a particular brand. If the label, the power brick, or the manual prints a different watt figure, type that figure.
Hours are the hours the machine is actually on. Eight hours is a common sleep block. It is not a rule. If you only run it for part of the break, change the hours. The engine-off box on the planner is a reminder of the break. It does not override the CPAP hours.
A phone-charger preset on the inverter calculator is a different job. Use it when you want one appliance and one battery. Use the planner when the fridge, a fan, and the CPAP share the same night.
DC cord or inverter
Some machines accept a 12 volt cord. Some only accept the AC brick that came in the box. Open the manual and match the plug you actually have.
If the machine is on a DC cord, the planner should be set to 12 V DC. The draw is then watts divided by 12, as amps, with no inverter efficiency subtracted. A 60 watt label is 5 amps at 12 volts for as long as it runs. Confirm the cord is rated for that current. A thin phone cable is not a CPAP cord.
If the machine is on an inverter, the battery also pays for inverter heat. The planner divides watt-hours by the efficiency you type. The default is 90 percent. A 60 watt load for 8 hours is about 533 watt-hours from the battery at that efficiency, before any other load. The inverter guide is where continuous watts and surge watts are separated. Surge is the wrong number for a night of breathing.
Do not backfeed an inverter into shore power. Do not run the brick from a socket that dies when the key is off, unless you have checked that the socket stays live. Company trucks often forbid a new wire to the batteries. Ask before you add one.
Water in the chamber
Many manuals tell you to use distilled water in a heated humidifier. Follow the manual for the machine you have. If that manual does not mention distilled water, do not invent a rule for it.
Buy the water before the trip if the manual asks for it. Truck stops do not always stock it. If you do not need the heat that night, turn the humidifier off and type the lower watt figure. Running the heater on an empty chamber wastes amp-hours and ignores the manual.
Empty the chamber when the manual says to. A closed sleeper is a small room. Standing water does not belong in a bin under the bunk.
Battery planning
Add the CPAP to the other loads that stay on with the engine off. A 12 volt fridge is usually the other large one. The fridge calculator uses Dometic's published lab average for one model. The planner can hold both.
Usable energy is amp-hours times voltage times the depth of discharge you are willing to use. Fifty percent is the cautious ceiling when the bank also has to crank the truck. Eighty percent is a planning figure for a lithium house battery, not a promise the battery is healthy. A starting battery that must crank in the morning is a bad only plan for a full night of CPAP plus a fridge. Shore power is the other feed, when the parking spot has a plug your cord can actually use.
On a phone, this table moves sideways. The first column stays put.
| Choice | What this page uses | What you should type instead |
|---|---|---|
| Humidifier off | 60 W planning default | The watt figure on your label or brick |
| Humidifier on | 90 W planning default | The heated figure in your manual, if it prints one |
| DC cord | Amps = watts ÷ 12, no inverter loss | The cord and the manual, not a guess |
| Inverter | Watts × hours ÷ efficiency | The efficiency on your inverter sheet |
| Other loads | Fridge, fan, lights, laptop if you enable them | Only the loads that are really on |
Screening, at the level of the official page
In the United States, FMCSA's page on driving when you have sleep apnea says the regulations do not specifically address sleep apnea. It also says a condition likely to interfere with safe driving cannot be medically qualified, and that once treatment is successful a driver may be medically qualified again. The medical examiner decides fitness. The January 2024 Medical Examiner's Handbook is the document that replaced the older bulletin. Read those pages. Read the official page rather than a summary.
In Canada, commercial drivers are covered by the national safety code item on medical standards, maintained through the Canadian Council of Motor Transport Administrators, with periodic medical exams. Transport Canada describes that framework on its commercial-vehicle safety page. A separate voluntary carrier program, the North American Fatigue Management Program, includes sleep apnea among the topics carriers can train on. Screening methods stay on those official pages.
- Commercial vehicle safety in Canada, Transport Canada
- Motor carrier safety research, Transport Canada, including the fatigue-management program
A worked night
Use your label if you have it. If you are only planning, the defaults are a starting point.
- Fridge, 12 volt, 1.03 amps for 10 hours. That is the Dometic CFX3 45 lab average, not a promise for a closed July cab. Watt-hours are 1.03 × 12 × 10, about 124 Wh, with no inverter loss.
- CPAP on an inverter, 60 watts for 8 hours, humidifier off, inverter efficiency 90 percent. Watt-hours from the battery are 60 × 8 ÷ 0.9, about 533 Wh.
- Together that is about 657 Wh, or about 55 amp-hours at 12 volts.
- A 200 amp-hour bank at 12 volts, using half of it, holds 1,200 Wh. The night fits, with surplus, if those are the only loads and the numbers match your labels.
- Turn the humidifier to the 90 watt planning default and the CPAP portion becomes 90 × 8 ÷ 0.9, about 800 Wh. The same bank still covers the fridge plus that CPAP. Add a laptop, a fan, and a 900 watt heater and it usually does not.
The power planner does this arithmetic for the loads you check. The inverter calculator is the one-appliance version. The fridge calculator is the compressor by itself.
What to buy, and what to skip
Buy the cord the manual lists. A DC cord, when the manual includes one, skips inverter loss. An AC brick needs an inverter whose continuous rating is at least 125 percent of the watt label. A 60 watt label points at a 150 watt continuous inverter on that rule, not at the surge number printed largest on the box.
Buy distilled water when the manual tells you to. Buy it before you leave, not at the last truck stop of the night.
Skip a plan that runs the machine from a cigarette-lighter socket you have not checked. Many of those sockets die with the key, and many are fused for a phone charger, not for a CPAP. Skip a heated humidifier left on all night on a starting battery that also has to crank the truck, unless the planner shows a surplus at 50 percent depth of discharge and you accept that limit. Skip any advice to change a pressure, skip a night, or pick a different machine than the one you were given. That decision is the clinician's and the examiner's.
Shore power, when the parking spot has a plug your cord matches, is the easy feed. The shore-power guide covers the plugs that do not interchange. Company trucks often forbid a new wire to the batteries. Ask before you add one.
Conclusion
Read the watt label, match the cord, and add the other loads in the planner. The examiner decides fitness. The official FMCSA and Transport Canada pages are linked above.
FAQ
Should I buy a DC CPAP instead of the machine I was given?
Keep the machine you were given. If its manual includes a DC cord, that cord avoids inverter loss. If it does not, use the brick and an inverter sized from the watt label.
Is 60 watts the draw of my machine?
No. Sixty watts with the humidifier off and 90 watts with it on are planning defaults. Read your label.
Who has to be screened?
FMCSA and Transport Canada publish the medical rules. The examiner decides fitness. Read the pages linked above.