Researchers in Finland suggest sleep disturbances may improve after retirement -- for those with secure pensions.

The study, published in the journal Sleep, found a sharp decrease in sleep disturbances in financially secure retirees. However, among the small number retiring early due to illness or disability the risk of sleep disturbances increased 46 percent.

The researchers looked at sleep in a group of French utility company workers retiring before age 60 with pensions at 80 percent of their salary. These workers' odds of having disturbed sleep in the seven years after retirement were 26 percent lower than in the seven years before retiring. The greatest reduction in sleep disturbance in the 14,714 participants was in those with depression or mental fatigue prior to retirement.

"We believe these findings are largely applicable in situations where financial incentives not to retire are relatively weak," study lead author Jussi Vahtera of the University of Turku in Finland said in a statement.

"In countries and positions where there is no proper pension level to guarantee financial security beyond working age, however, retirement may be followed by severe stress disturbing sleep even more than before retirement."