The night driving fatigue rules under the Heavy Vehicle National Law (HVNL) exist for a simple reason: driving at night is when fatigue risk is at its worst. Research consistently shows that fatigue-related crashes peak between 2 am and 6 am, when the body’s circadian rhythm hits its lowest point. A second, smaller peak hits in the early afternoon between 2 pm and 4 pm. For heavy vehicle drivers covering long stretches of highway in the dark, these are not abstract statistics. They are the hours when reaction times slow, lane-keeping deteriorates, and microsleeps become a real danger.
The Heavy Vehicle National Law (HVNL) treats night driving as a distinct risk category. It does not simply apply the same work and rest limits around the clock. There are specific night rest break requirements, a combined “long/night work time” cap for BFM-accredited drivers, and – since 1 August 2026 – an expanded “unfit to drive” duty that applies to every heavy vehicle over 4.5 tonnes GVM, regardless of the hour.
This article breaks down exactly what those rules require, how night work time is counted, and what operators and schedulers need to do to stay compliant.
Why Night Driving Fatigue Rules Exist
The HVNL does not treat all hours equally because the human body does not treat all hours equally.
Your circadian rhythm is a roughly 24-hour internal clock that regulates alertness, body temperature, and hormone production. Between about midnight and 6 am, that clock pushes hard toward sleep. Alertness drops. Reaction times get longer. The ability to maintain a consistent lane position – a standard measure of driving impairment – deteriorates significantly.
This is not just theory. In NSW alone, 78 people died in fatigue-related crashes in 2024, a 47 per cent increase from 53 deaths in 2023. Heavy vehicles made up only 2 per cent of NSW motor vehicle registrations, yet heavy vehicle drivers accounted for around 26 per cent of those fatigue-related deaths. Nationally, 179 lives were lost in crashes involving a heavy vehicle in 2024, which the NHVR described as “devastating and entirely preventable.”
The HVNL addresses this risk through two main mechanisms: mandatory night rest breaks and caps on long/night work time accumulation.
Night Rest Breaks: The Core Requirement
Under every hours option (Standard Hours, BFM, and now ACH), drivers of fatigue-regulated heavy vehicles must take night rest breaks at regular intervals.
A night rest break is defined as 7 continuous hours of stationary rest taken between the hours of 10 pm on a day and 8 am the next day, using the time zone of the driver’s base. A continuous 24-hour stationary rest period that includes that 10 pm to 8 am window also counts as a night rest break.
Stationary rest means the driver must be either out of the heavy vehicle entirely or in an approved sleeper berth of a stationary vehicle. Resting in the cab while the engine is running and someone else drives does not count for this purpose (unless the vehicle has a compliant sleeper berth and the vehicle is stationary).
How Often Night Rest Breaks Are Required
The frequency depends on which hours option the driver operates under:
Standard Hours (solo driver) Night rest breaks must be taken within the regulated intervals set out in the NHVR’s work and rest hours tables. For a standard hours solo driver, the 14-day counting period requires specific night rest breaks. The daily requirement is straightforward: within any 24 hours, a solo driver needs a minimum of 7 continuous hours of stationary rest, and across each 7 days, at least one of those must qualify as a night rest break.
BFM (solo driver) Within any 14 days, a BFM solo driver must take at least 4 night rest breaks, with at least 2 taken on consecutive days. This gives BFM drivers more flexibility for occasional night runs, but it does not eliminate the night rest requirement.
ACH (Alternative Compliance Hours) Since 1 August 2026, ACH has replaced BFM and AFM for new accreditations under the Heavy Vehicle Accreditation (HVA) scheme. Night rest conditions under ACH are set on the operator’s accreditation certificate. Operators transitioning from BFM should check their certificate for the specific long/night work conditions that apply.
Long/Night Work Time: The Combined Cap
This is where many operators get tripped up. The HVNL does not treat “long hours” and “night hours” as separate categories. They are combined under a single definition: long/night work time.
Under the Heavy Vehicle (Fatigue Management) National Regulation, long/night work time means any work time that is either:
- In excess of 12 hours in 24 hours, or
- Between 12 midnight and 6 am (using the time zone of the driver’s base)
Both types count toward the same running total.
The 36-Hour Cap Under BFM
A solo driver operating under BFM must not exceed 36 hours of long/night work time in any 7 days.
Once that 36-hour cap is reached, the driver cannot do any more long/night work until the accumulated total drops below 36 hours. In practical terms, that means the driver either:
- Cannot exceed 12 hours of work in 24 hours, or
- Cannot work between 12 am and 6 am
…until the 7-day rolling total clears enough room.
How the Count Works in Practice
Here is where the detail matters. Say a BFM solo driver works 13 hours between 6 am and 11 pm. All of those hours fall outside the midnight-to-6 am window. But 1 hour exceeds the 12-hour daily threshold. That driver has accumulated 1 long/night hour for the count.
Now consider a different driver who works 14 hours between 1 pm and 6 am the next day. Those hours include 6 hours between midnight and 6 am. That driver accumulates 6 long/night hours, not 8 (you do not double-count the overlap between the “over 12 hours” component and the “midnight to 6 am” component across the same 24-hour period).
A third scenario: a driver works 13 hours between 5 pm and 9 am the next day, including the full midnight-to-6 am window plus 8 am to 9 am. That driver accumulates 7 long/night hours – 6 hours for the midnight-to-6 am window, plus 1 hour for the work time exceeding 12 hours that falls outside that window (the 8 am to 9 am portion).
Overlapping Counting Periods
When 24-hour counting periods overlap, and both contain long/night work hours, those hours are counted only once. They are then totalled for the period the limitation applies to (for example, 36 hours in 7 days under BFM). The NHVR is explicit about this: do not double-count hours that fall across overlapping periods.
AFM and ACH Conditions
For drivers under AFM or ACH, long/night work conditions are set on the accreditation certificate. If the certificate does not include a long/night work condition, there may be no specific cap on long/night hours beyond the general work and rest limits. Operators unsure about their conditions can contact the NHVR fatigue management team at [email protected].
The Expanded “Unfit to Drive” Duty
Since 1 August 2026, the amended HVNL has expanded the “unfit to drive” duty under Section 228(1). Previously, the obligation not to drive while impaired by fatigue applied only to fatigue-regulated heavy vehicles (generally over 12 tonnes GVM).
Now, a driver must not drive any heavy vehicle over 4.5 tonnes GVM while impaired by fatigue or otherwise unfit to drive – even if the driver is within their permitted work and rest limits.
This is critical for night driving. A driver can be fully compliant with every work and rest rule and still be too fatigued to drive safely. The NHVR’s own guidance is direct about this: the maximum work and minimum rest limits are outer boundaries, not guarantees of fitness.
The expanded duty also covers impairment from illness, injury, mental health conditions, medication, alcohol, and drugs. For night drivers who may have had disrupted sleep or who are working a second job during the day, this expanded duty closes a gap that previously existed for lighter heavy vehicles.
Chain of Responsibility: It Is Not Just the Driver’s Problem
Under the HVNL’s Chain of Responsibility (CoR) provisions, the obligation to manage night driving fatigue does not sit with the driver alone. Every party in the supply chain has a primary duty to ensure, so far as is reasonably practicable, the safety of their transport activities.
The NHVR’s Regulatory Advice on fitness to drive specifically calls out a common and dangerous scenario: drivers working multiple jobs, such as a secondary job during business hours followed by heavy vehicle driving at night. If an operator knows or ought to know that a driver is arriving for a night shift already fatigued from other work, failing to address that risk is a CoR problem.
Schedulers have particular exposure here. Building rosters that routinely require driving during the 2 am to 6 am window without adequate recovery time is not just poor practice – it is the kind of systemic risk that the CoR primary duty is designed to catch.
Since the August 2026 amendments, safety management system (SMS) audit findings are now admissible as court evidence for CoR breaches. An operator whose SMS identifies night fatigue as a risk but fails to implement controls is creating a documented trail of non-compliance.
The penalty ceiling for a Category 1 CoR breach now sits at $4,230,550 for a body corporate and $436,850 plus up to 5 years imprisonment for an individual.
Practical Steps for Managing Night Driving Risk
Compliance with the letter of the work and rest rules is the baseline. Actually managing night fatigue risk requires more.
Scheduling and Rostering
Build rosters that limit consecutive nights and, where possible, avoid scheduling the highest-risk freight movements between 2 am and 6 am. Where overnight driving is unavoidable (and in many freight operations, it is), ensure drivers have had adequate sleep opportunity before the shift starts.
The NHVR recommends rest every two hours during driving, and this is even more important at night. Short breaks of 15 to 20 minutes can slow the onset of fatigue, but they do not replace proper sleep.
Two-Up Driving Arrangements
Two-up driving, where two drivers share the driving of one fatigue-regulated heavy vehicle, is one way to manage night driving risk. Both drivers must operate under a two-up work option (Standard Hours two-up, BFM two-up, or ACH two-up) and must independently meet the work and rest requirements.
The NHVR recommends that two-up drivers only use an approved sleeper berth for continuous rest while the vehicle is moving before taking their major rest break – not as a substitute for it.
Fatigue Detection Technology
In-cab fatigue detection cameras using PERCLOS (percentage of eyelid closure) and head-position tracking can provide real-time alerts when a driver shows signs of drowsiness. These systems are particularly valuable during night shifts when the biological drive toward sleep is strongest.
The 2026 Master Code now explicitly includes fatigue and distraction detection technologies (FDDT) among the controls operators should consider. While not mandatory, their inclusion in the Master Code means a court could consider their absence when assessing whether an operator took “reasonably practicable” steps.
Work Diary and EWD Recording
Night driving creates specific recording obligations. Any work performed between midnight and 6 am counts toward the long/night work time tally and must be accurately recorded. Drivers using paper work diaries or electronic work diaries (EWDs) need to ensure these hours are captured correctly, because errors in night-time recording are exactly the kind of thing an NHVR audit or roadside inspection will flag.
Operation Ambit II in March 2026 intercepted more than 6,100 vehicles and found that false or misleading records had increased by 42 per cent compared to earlier operations. Fatigue offences made up 23 per cent of all detected breaches in 2025, and administrative fatigue offences were up more than 10 per cent. Getting the recording right is not optional.
Frequently Asked Questions
Does the HVNL ban night driving for heavy vehicles?
No. The HVNL does not prohibit night driving. It imposes specific requirements around night rest breaks, caps on long/night work time accumulation (under BFM), and a general duty not to drive while impaired by fatigue. Night driving is permitted within these limits.
What hours count as “night” under the HVNL?
The long/night work time definition uses 12 midnight to 6 am (in the time zone of the driver’s base). Night rest breaks must fall within the 10 pm to 8 am window. These are two separate definitions used for different purposes.
Do Standard Hours drivers have a long/night work time cap?
The 36-hour cap on long/night work time in 7 days applies specifically to BFM solo drivers. Standard Hours drivers do not have a separate long/night work time cap, but they must still take the required night rest breaks and must not drive while impaired by fatigue.
What happens if a BFM driver exceeds 36 hours of long/night work in 7 days?
The driver must stop doing any work that would add to the long/night total until the 7-day rolling count drops below 36 hours. That means no work beyond 12 hours in a 24-hour period and no work between midnight and 6 am. Exceeding the cap is a fatigue breach.
Has the “unfit to drive” rule changed for night drivers?
Yes. Since 1 August 2026, the expanded unfit-to-drive duty applies to all heavy vehicles over 4.5 tonnes GVM – not just fatigue-regulated vehicles over 12 tonnes. This means drivers of medium heavy vehicles are now also covered, even if they are not otherwise required to keep a work diary.
How does time zone affect night work counting?
Long/night work time between midnight and 6 am is measured using the time zone of the driver’s base. If a driver’s base is in Sydney but they are driving through South Australia (which is 30 minutes behind), the midnight-to-6 am window is still counted based on Sydney time.
