Drowsiness reduces reaction time, a critical element of safe driving and riding, it also reduces alertness and concentration. The ability to perform attention-based activities, such as riding is impaired and decision making can be badly affected, as information cannot be quickly processed by a person who is tired.

Fatigue is estimated to be a contributory factor in up to 20% of road collisions. These types of crashes tend to be high speed impacts resulting in death or serious injury, because a driver/rider who has fallen asleep cannot brake or swerve.

Riders will be aware that they are feeling sleepy, and must make a conscious decision to stop for a rest. Ignoring or underestimating the risks of continuing a journey when tired is naive and irresponsible.

Collisions involving fatigue are most likely to happen:

• on long journeys on monotonous roads, such as motorways
• between 2am and 6am
• between 2pm and 4pm (especially after eating, or taking even one alcoholic drink)
• after having less sleep than normal
• after drinking alcohol/taking drugs
• if taking medicines that cause drowsiness
• after long working hours or on journeys home after long shifts, especially night shifts.

Most methods drivers or riders use to try to keep themselves awake and alert are ineffective, and should only be regarded as emergency measures to allow time to find somewhere safe to rest. Drinking at least 150mg of caffeine and taking a nap of around 15 minutes are the only measures that help to reduce sleepiness, for a temporary period.

Bikers who notice a pattern of feeling sleepy when riding may have an undiagnosed sleep disorder, such as sleep apnoea. Some may be unwilling to seek help because they fear losing their licence. However, there are established treatments for sleep apnoea which allow licence retention. Anyone suspecting that they have a sleep disorder is strongly advised to contact their GP.

Plan your journey to include regular rest breaks - at least 15 minutes every two hours - and if necessary plan an overnight stop.

At this time of year especially, drivers and motorcyclists may be making journeys in the early hours or late at night when travelling to or from an airport or ferry port. Festival goers and holiday makers should follow our advice to never drive or ride when feeling sleepy, or if they have had little sleep in the previous 24 hours.