Roads Policing - Driver Fatigue

The killer you won’t see coming.

Driver fatigue is a real risk to your safety and that of other road users and significantly increases crash risk by reducing reaction time, attention, and decision-making. It is a recognised factor in many serious collisions in Ireland and internationally. According to the European Road Safety Observatory report fatigue is a major factor in a large proportion of road traffic collisions (10 – 20%).

Fatigue is a recurring contributory factor in collisions, especially on long rural roads, motorways, and during night-time or early-morning hours.
Fatigue-related collisions often resemble impaired driving: single-vehicle run-off-road crashes, crashes on long straight roads, or incidents with limited braking or steering input before impact.
Research shows driving after 17–19 hours awake produces impairment comparable to being over legal alcohol limits; high-risk windows include midnight – 06:00, and mid-afternoon.

Dangers of driver fatigue

Slower reaction times and reduced vigilance: delayed responses to hazards or sudden braking ahead.
Microsleeps: brief involuntary sleep episodes; at 100 km/h (≈62 mph), a 2-second microsleep covers ~56 m.
Impaired judgment and risk assessment: lane drifting, poor speed control, misjudging gaps.
Increased likelihood of single-vehicle collisions and high-speed impacts due to lack of corrective action.
Cumulative risk from chronic sleep debt, which compounds momentary sleepiness and crash risk.

Recognising dangerous sleepiness while driving

(If you experience any of these signs, stop driving as soon as it is safe.)

Heavy eyelids, difficulty keeping eyes open, frequent blinking.
Repeated yawning, head nodding, or stretching to stay awake.
Memory lapses: not recalling the last few miles or missing exits/signs.
Difficulty concentrating or wandering thoughts.
Drifting between lanes, hitting rumble strips, needing to overcorrect.
Sudden changes in driving tempo or increased irritability.
Increased inattention during monotony (long straight roads, night, post-lunch).

Practical tips to prevent and manage fatigue

Pre-trip planning

Get adequate sleep before a long drive (7–9 hours for most adults).
Avoid starting long trips after a late night; schedule to avoid midnight–06:00 and mid‑afternoon when possible.
Plan regular breaks: at least every 2 hours or every 100–130 km for 15–20 minutes.
Share driving duties on long journeys where possible.

During the drive

Stop at the first sign of sleepiness; take a 20–30 minute nap in a safe rest area.
Use caffeine strategically: 100–200 mg can boost alertness within 20 – 30 minutes; combine with a short nap for better effect.
Take short walks, stretch, get fresh air during breaks.
Avoid heavy meals before driving and excessively warm cabin temperatures.
Don’t rely on open windows, loud music, or smelling salts as primary countermeasures — they are short-lived.

The following groups are particularly at risk of Driver Fatigue

Young Drivers

Adolescents need more sleep than adults but all too often they don’t get enough sleep. Late night driving combines with sleep deprivation is a dangerous combination

Professional Truck Drivers

Driver fatigue is a particular problem for national and international truck drivers as the demands of the long-haul transport industry interfere with optimal rest. Truck drivers typically work long hours on what are predominantly dual carriageways or motorways.

Taxi Drivers

These drivers are also prone to fatigue related risks as their work lends itself to working long hours of driving during the night.

Shift Workers

While the extent of fatigue experienced by shift workers can vary widely across so many different areas of work, overall shift work is associated with chronic sleep loss which increases collision risk.

Fatigue is a serious but preventable road risk.

Recognise the signs, plan trips and breaks, use short naps plus caffeine when needed, treat sleep disorders, and support road and workplace measures that reduce fatigue-related crashes.